University Physics Students and the Curse of "Naive" Physics
April 27 2009 at 5:26 PM
(Premier Login aceputt) Forum Owner from IP address 24.28.240.12
Dear Folks,
I constantly have to harp on the fact that not too many golfers understand physics at the most rudimentary level, and this usually underlies some quite goofy "explanations" of what is happening in putting and what the golfer "needs" to do to make the right stuff happen. Here's a little tale about university physics students and a PhD graduate student in philosophy -- 53% of the class still have "crazy" notions about reality after taking the class:
About 6-7 years ago, I was in a philosophy class at the University of Wisconsin, Madison (good science/engineering school) and the teaching assistant was explaining Descartes.
He was trying to show how things don't always happen the way we think they will and explained that, while a pen always falls when you drop it on Earth, it would just float away if you let go of it on the Moon. My jaw dropped a little. I blurted "What?!" Looking around the room, I saw that only my friend Mark and one other student looked confused by the TA's statement. The other 17 people just looked at me like "What's your problem?" "But a pen would fall if you dropped it on the Moon, just more slowly." I protested.
"No it wouldn't." the TA explained calmly, "because you're too far away from the Earth's gravity." Think. Think. Aha! "You saw the APOLLO astronauts walking around on the Moon, didn't you?"
I countered, "why didn't they float away?"
"Because they were wearing heavy boots." he responded, as if this made perfect sense (remember, this is a Philosophy TA who's had plenty of logic classes). By then I realized that we were each living in totally different worlds, and did not speak each others language, so I gave up.
As we left the room, my friend Mark was raging. "My God! How can all those people be so stupid?" I tried to be understanding. "Mark, they knew this stuff at one time, but it's not part of their basic view of the world, so they've forgotten it. Most people could probably make the same mistake."
To prove my point, we went back to our dorm room and began randomly selecting names from the campus phone book. We called about 30 people and asked each this question: 1
1. If you're standing on the Moon holding a pen, and you let go, will it
a) float away,
b) float where it is,
or c) fall to the ground?
About 47 percent got this question correct. Of the ones who got it wrong, we asked the obvious follow-up question:
2. You've seen films of the APOLLO astronauts walking around on the Moon, why didn't they fall off?
About 20 percent of the people changed their answer to the first question when they heard this one! But the most amazing part was that about half of them confidently answered, "Because they were wearing heavy boots."
MORE ON THE BURNING QUESTION OF HEAVY BOOTS
I decided to settle this question once and for all. Therefore, I put two multiple choice questions on my Physics 111 test, after the study of elementary mechanics and gravity.
13. If you are standing on the Moon, and holding a rock, and you let it go, it will:
(a) float away
(b) float where it is
(c) move sideways
(d) fall to the ground
(e) none of the above
25. When the Apollo astronauts wre on the Moon, they did not fall off because:
(a) the Earth's gravity extends to the Moon
(b) the Moon has gravity
(c) they wore heavy boots
(d) they had safety ropes
(e) they had spiked shoes
The response showed some interesting patterns! The first question was generally of average difficulty, compared with the rest of the test: 57% got it right. The second question was easier: 73% got it right. So, we need more research to explain the people who got #25 right but did not get #13 right!
The second interesting point is that these questions proved to be excellent discriminators: that is, success on these two questions proved to be an extremely good predictor of overall success on the test. On the first question, 92% of those in the upper quarter of the test score got it right; only 20% of those in the bottom quarter did. They generally chose answers (a) or (b). On the second question, 97% in the upper quarter got it right and 33% in the lower quarter did. The big popular choice of this group was (c)...33% chose heavy boots, followed closely by safety ropes at 27%.
A telling comment on the issue of fairness in teaching elementary physics: Two students asked if I was going to continue asking them about things they had never studied in the class."
Re: University Physics Students and the Curse of "Naive" Physics
April 27 2009, 9:16 PM
When I was in graduate school earning my engineering degree, I remember reading an article about a physics class at one of the top schools (MIT, CalTech, in that class) where the professor gave a concepts test at the end of the semester, with quite shameful results.
This was an exam that didn't use any equations because a lot of people are good at memorizing equations and just putting in the knowns until the 1 unknown pops up and solve for it without actually knowing anything about what the equation says. My experience is that there are an awful lot of physics, math, and engineering students who get good grades this way but know very little of what is actually happening.
So many students (A & B included) don't connect the concept that you make your car go faster by increasing its acceleration (hence, the correct name of that pedal, the accelerator). Or that when you pedal your bike faster, you are increasing the acceleration on the bike. They don't get that the new increased speed is the result of a rebalance of the new acceleration and drag forces. They memorize F=ma, but don't actually know what it means.
It is one of the toughest things to overcome -- learning that your instincts are wrong. This is true in the physics classroom, and this is true in golf. Higher speed is the result of increased acceleration, and longer drives are the rest of not using your hands, etc. You have to fight to overcome your first instincts of how position, velocity, and acceleration are related in physics and your first hit instincts in golf.
At the end of the article, there were two main conclusions. 1) That even though you can achieve grades of As and Bs in physics classes, it doesn't mean that you actually know anything and 2) that the way classes are typically taught (and I'd add graded and tested) isn't working all that well because they don't adequately test if the students do know basic concepts or not.
In my own experience, there were several students I graduated with who had almost perfect 4.0 GPAs who I would never want to work at the same plant as they do because while they were excellent test-takers and homework-doers, they really had no idea of what the equations they were using were saying and vice-versa there were several students I graduated with who were average to below average students who weren't very good at the mathematical side of the classes, but who always had a very good grasp of what was occurring physically (like in the lab or something similar).
This message has been edited by notBignose from IP address 65.101.164.66 on Apr 27, 2009 9:23 PM
"Common sense beliefs about motion are generally incompatible with Newtonian theory. Consequently, there is a tendency for students to systematically misinterpret material in introductory physics courses."
"Common sense beliefs are very stable, and conventional physics instruction does little to change them."
"Conventional instruction has little effect on the students basic knowledge state."
"The small gain in basic knowledge under conventional instruction is all the more disturbing when one considers the uniformly low levels of the initial knowledge states shown in Table I. This means that throughout the course the students are operating with a seriously defective conceptual vocabulary, which implies that they continually misunderstand the material presented."
"Diagnostic test results show that a students initial knowledge has a large effect on his performance in physics, but conventional instruction produces comparatively small improvements in his basic knowledge. The implications of failure on the part of conventional instruction could hardly be more serious, for we are not talking about a few isolated facts that students failed to pick up. Ones basic physical knowledge provides the conceptual vocabulary one uses to understand physical phenomena. A low score on the physics diagnostic test does not mean simply that basic concepts of Newtonian mechanics are missing; it means that alternative misconceptions about mechanics are firmly in place. If such misconceptions are not corrected early in the course, the student will not only fail to understand much of the material, but worse, he is likely to dress up his misconceptions in scientific jargon, giving the false impression that he has learned something about science."
You are quite right about the inability to comprehend F=ma, but your personal language is similar to the "wrong" language of most people. You write:
"So many students (A & B included) don't connect the concept that you make your car go faster by increasing its acceleration (hence, the correct name of that pedal, the accelerator). Or that when you pedal your bike faster, you are increasing the acceleration on the bike. They don't get that the new increased speed is the result of a rebalance of the new acceleration and drag forces. They memorize F=ma, but don't actually know what it means. It is one of the toughest things to overcome -- learning that your instincts are wrong. This is true in the physics classroom, and this is true in golf. Higher speed is the result of increased acceleration, and longer drives are the rest of not using your hands, etc. You have to fight to overcome your first instincts of how position, velocity, and acceleration are related in physics and your first hit instincts in golf."
The Newtonian "correct" language is that "CONSTANT" acceleration leads to increasing velocity, not your language of "increasing acceleration". Your sense of "adding" acceleration in order to add velocity is not Newtonian, but "medieval" physics in conception.
And the phrase learning that your instincts are wrong confuses the "conscious misconceptions" with what the "instincts" represent. Actually, the implied "ignorance" of instincts about real physics is exactly backwards: the "instincts" get the real physics right, without language-based and concept-based misconceptions, and it is the "conscious" mind that does NOT get the physics right. The conscious mind is indeed "ignorant" in the usual sense of the word, but the instincts are brilliant compared to the misconceptions of the conscious mind. This is especially relevant to how the body and instincts perform the physics of motion -- by instincts, without the interference of the "dumb" conscious mind.
It's more than 4 centuries since Newton's Philosophiæ Naturalis Principia Mathematica, was published in 1687, and is considered to be among the most influential books in the history of science, laying the groundwork for most of classical mechanics. Yet the intuitive 'physics' of the subjective masses still hold them in total ignorance of Newtonian physics.
Golf is perhaps most adversely impacted by pre-Newtonian intuitive physics, because golfers only feeel themselves and use their subjective senses to interpret their golf swing and putting stroke. Incredible ...!!!!
I am amazed at the ignorance of so-called golfswing gurus who still proclaim: "use centrifugal force" to hit the ball ... yet none of them can explain how a subjective center-fleeing "force" can suddenly change it's vector direction by 90º and "hammer" the ball at impact...!!!
Another ignorant manifestation is the incorrect application of Newton's Laws of Motion, particularly invoking the Third Law when attempting to validate their concept of "equal and opposite" forces. I always thought that equal and opposite forces creates a static condition, a special condition of the Third Law ... but no, those great and accomplished golf gurus use Newton's laws helter-skelter ... and naive, ignorant golf wannabes will believe and pay money for the false advise.
Maybe it is 'money' that makes the world go round ...!!!!!
Geoff .. just to add more fuel to the fire ... most everybody thinks in terms of linear F = ma .. whereas for the golfswing one should think in terms of angular T = Ia(alpha). Of course this would render most everybody ignorant if they had to conceptualize first moment of inertia and angular acceleration. And then there is the confusion between F and T .. since we all know that Force is not Torque. ("It all feeels the same to me!!")
I shouldn't denigrate good golfers who are trying to explain their golfswings to the eager unathletic masses who attempt to swing a golf club and erroneously believe all will be well if somebody would just provide them with that magical 'tip' that will propel them to break 100. Invoking Newtonian physics is a lost cause but it certainly impresses, regardless if it's right or wrong!!
It's easier and more social to define the golfswing and putting stroke in subjective terms that can be shared emotionally, because emotions can be equated to "feeel". You don't need intelligence to share feeelings .. everybody has "feeel" and "feeelings" ... it's the "human" equation.
Your thought about "forces always act in equal and opposite directions" meaning something "static" is typical "naive physics" figuring-out. What Newton's Third Law really means is that when two inanimate objects collide (or one collides against another), there is only ONE FORCE acting on both objects. The effect of this force on the two objects is not, however, "static" or "equal" unless the objects are equal in shape, mass, density, etc., and collide with centers of mass head-on. Usually, a big truck smashes into a small car. Such a head-on collision has ONE FORCE acting on both objects equally in opposite directions, but the effects are not the same. The big truck experiences a bump and slows down a little while still going forward, but the small car gets SMASHED FLAT and is sent rocketing backwards! Nothing "static" about that!
Although physicists speak about "pairs" of equal and opposite "forces", they might as well speak only about a single "force" that acts in two directions equally on two objects during a collision. There is no functional difference in these two conceptualizations, once the forces are accepted as "equal and opposite". Here is the usual explanation:
"Newton's third law: All forces in the universe occur in equal but oppositely directed pairs. There are no isolated forces; for every external force that acts on an object there is a force of equal magnitude but opposite direction which acts back on the object which exerted that external force. In the case of internal forces, a force on one part of a system will be countered by a reaction force on another part of the system so that an isolated system cannot by any means exert a net force on the system as a whole. A system cannot "bootstrap" itself into motion with purely internal forces - to achieve a net force and an acceleration, it must interact with an object external to itself."
"Without specifying the nature or origin of the forces on the two masses, Newton's 3rd law states that if they arise from the two masses themselves, they must be equal in magnitude but opposite in direction so that no net force arises from purely internal forces."
"Newton's third law is one of the fundamental symmetry principles of the universe. Since we have no examples of it being violated in nature, it is a useful tool for analyzing situations with are somewhat counter-intuitive. For example, when a small truck collides head-on with a large truck, your intuition might tell you that the force on the small truck is larger. Not so!"
The DEEP MYSTERY here is just the symmetrical simplicity of the universe. No inanimate object carries around any (net) INTERNAL force that can act either on itself or on another object. That "rejects" the medievalist "impulse" concept of forces being "put in" objects. In this sense, the universe does not allow changing a mass by "putting speed into it". That's not how "force" operates. But there is a MUCH DEEPER MYSTERY, because according to Special Relativity objects near the speed of light become heavier and time slower. But that's "relative" to something else. In itself, an object at ANY speed cannot have anything "put into it" like a force that can cause something on another object later. Masses are not kangaroos with secret pouches hiding little kangaroos of force. "No net force can be generated within the system [internally] since all internal forces occur in opposing pairs. The acceleration of the center of mass is zero."
The whole concept of "force" is pretty fuzzy, despite what physicists may claim about the ontological reality of "force". This aspect of the science is highlighted by contrasting the concept of "force" with that of "energy". How do these two formulae relate to each other?
F = m*a
E = m*c^2
Well, m = F/a and m = E/c^2, so F/a = E/c^2.
Rearranging:
F = E*a/c^2
Where'd the "mass" go? Where's the "object" now? This formula says that a "force" is just a change of energy over a space in time. Okey dokey. There is no "mass" apart from its energy. "The mass of an object is a fundamental property of the object; a numerical measure of its inertia; a fundamental measure of the amount of matter in the object." Okey dokey, what is "inertia"? No one seems to know the answer to that one.
The interesting point that all objects either remain at rest or remain at constant velocity until operated upon by an external force means that in the absence of force, ALL OBJECTS have ZERO acceleration at their center. That sounds akin to "inertia", but why is either situation the case in our universe? Why do objects internally never have anything bu ZERO acceleration at the center, and why does mass have inertia?
Ultimately, this game peters out in the defining of the units for E and F by a committee of scientists all speaking the same language and no other language (mathematics / symbolism). What the hell is a "Newton" and what is it's relation to an "Erg"? Who knows, since it doesn't advance the understanding of the concepts or explain reality more clearly. Units typically codify mathematical relations, but mathematical relations are usually simple "observations" expressed in symbols in a simplistic correlation (equal to, greater than, etc.), and are not "propositions that reveal reality's inner secret." F = m*a is really just an observation, and not something Newton derived by experimental fact gathering and deductive reasoning from other known formulae. E = m*c^2, however, is in fact derived from other formulae (the frequency and wavelength of light equations) and the deductive reasoning that follows from assuming that nothing exceeds the speed of light, leading to the conclusion that space and time are not separate but interact as a unified manifold.
The leading contender for "what is inertia" and "how does it come about" is probably the theory that inertia is simply the result of the relationship between one object and the rest of the universe's mass. The gravitational forces between one object and the rest of the universe "causes" inertia to be the way it is, and all masses that are the same magnitude and are at the same relative velocity all have the SAME inertia despite being located in different parts of the universe. That is, so far as anyone yet can tell. There is a HUGE assumption in the basic homogeneity of the "overall" density of the universe for shape and mass distribution that is probably not true, so theoretically inertia may differ in a very minor way on exact locations. Mass X in Moscow may not really have identical inertia if twin Mass X is located on the Dark Side of the Moon or halfway between Double Stars. The way this concept of inertia makes sense is to conceive of ANY location in the universe as ALSO the CENTER OF MASS of the whole universe. This is just what Cosmologists today say when describing the universe. That's not very "common sense", is it?
"All mechanical quantities can be expressed in terms of three quantities [i.e., mass, length or space, and time]." Apart from this, the concepts like "force" and "energy" are somewhat concocted in an effort to get a good bead on reality. A "force" is just what is said to correspond to what happens when a given mass changes location in space over a certain time. The faster and heavier and farther the change, the greater the "force". Energy is probably real, but I have grave doubts that "force" really means much. It's probably an outdated concept that should be jettisoned entirely.
No, you have to increase your acceleration in a car to go faster.
It is a force balance that determines how fast you go.
The positive force is the acceleration caused by the engine burning gasoline. The negative force (and either one can be the "positive" or "negative" one, all that is important is to realize that they act in opposite directions) is the drag from the ambient atmosphere on the car.
Let's just assume a straight road and no wind for simplicity.
This situation can be written as:
dv/dt (change in the car's velocity) = F_drag - F_engine
Drag is very highly velocity dependent (F_drag=F_drag(v)), drag is normally proportional to about velocity squared (the actual details can be very messy and aren't all the important to the discussion at hand). The force the engine puts out is dependent on how far you depress the accelerator.
At constant speed, dv/dt = 0, and thusly F_drag = F_engine.
So, let's say you have the pedal down 1/2 way and going a constant speed.
F_engine(pedal=1/2) = F_drag(v). You can solve this equation for v, call it v_1, which is the constant velocity that is attained for a given amount of pedal depression.
Now, say you wanted to go faster at again a constant speed, let's call this v_2.
Re-write the equation for v_2 -- F_drag(v_2) = F_engine and you can solve for the new amount of force the engine has to put out to achieve the desired speed.
And, now that we know the force the engine has to be generating, and recalling that F=ma, we find the new acceleration the engine must be producing to achieve the newer speed. The acceleration needed to achieve v_2>v_1 is greater than the previous acceleration a_2>a_1.
Thusly, my statement is correct -- in order to achieve a higher velocity, you have to increase the acceleration of the car, because the increased acceleration is the increase in force the engine puts out which determines the velocity that balances the new engine force with the drag force.
Sorry, your description is not Newtonian. Ask any high school physics teacher. F=ma means "no acceleration, no force". If a=0, F=0. Simple.
The "force" is spoken of correctly as "what causes the acceleration". A "force" that produces 1g of acceleration from the motors of a rocket ship "accelerates" the rocket ship with a constant rate of increasing velocity, but the "acceleration" rate is CONSTANT and not increasing. A constant acceleration makes the rocket ship go faster and faster and faster and faster and faster and faster .... etc.
A ball with ZERO velocity (at Time 1) is "accelerated" with a FORCE from zero to velocity X (at Time 2) in so many seconds (Time 2 - Time 1), so the RATE of acceleration over this time is fixed and not increasing. There was ZERO acceleration before Time 1, and the Force applied accelerated the ball to Velocity X. There is no INCREASE of acceleration; there is the application of a Force to the ball of a certain magnitude that produced the change in velocity in a given amount of time.
It is of course possible to apply unequal forces over a given time span, and this causes changing rates of acceleration. A downswing with an increasing rate of acceleration versus a natural pendular pattern of downward acceleration will result in "faster" putter head velocity at the bottom of the stroke. But one can arrive at this identical velocity with a variety of acceleration patterns and timings.
The SAME force will accelerate the same two masses with exactly the same rate of acceleration. Force X1.03 will accelerate these two objects from 10 mph to 20 mph in one second, so the RATE of acceleration is 10 mph/s ("Acceleration 1"). Later, when Force X1.03 is AGAIN applied to both objects, both objects will increase AGAIN at the SAME rate of acceleration (10 mph/s) and at the end of one second both will have increased speed from 20 mph to 30 mph ("Acceleration 2") . Now if there is a third object of the identical mass in this world that is currently traveling at 5 mph, and the SAME Force X1.03 is again applied this time to all three objects, after one second the third object has accelerated at the rate of 10 mph/s from 5 mph to 15 mph, and the other two have accelerated at the SAME rate of 10 mph/s from 30 mph to now 40 mph ("Acceleration 3"). The same force applied identical times results in three identical accelerations, not one acceleration and then an INCREASED acceleration and then another INCREASED acceleration. It's the same with accelerating a car three times: the same force applied three times equally will accelerate the car from speed 1 then to speed 2 then to speed 3, and the rate of acceleration all three times is the same, not getting bigger each step up in velocity.
A car that is going at a constant velocity has NO FORCE making it go faster (or slower). Forgetting friction and air resistance, any object in constant motion is undergoing NO FORCE. No force, no acceleration; no acceleration, no change in velocity. No change in velocity, no force and no acceleration.
Your example of the car changing velocity is not an INCREASE of acceleration, since a car at any steady velocity has NO ACCELERATION AT ALL. There is no acceleration to increase. Acceleration does not "hang around" after the force has been applied. And the force does not either.
Even though you oppose the force of the engine against the force of drag, when the two forces are equal, there is NO ACCELERATION and merely a steady velocity. So far as the object is concerned, when two forces equally oppose one another, the object experiences NO FORCE. No force, no acceleration. "Newton's Second Law [F=ma] applies to a wide range of physical phenomena, but it is not a fundamental principle like the Conservation Laws. It is applicable only if the force is the net external force." No "net" force, no change in velocity.
Again, the REAL problem here is twofold: faulty conceptualization and faulty language to embody the faulty conceptualization. If you can't say it, you don't know it; and if you can't say it correctly, you don't correctly know it.
In your case, here again is your language:
"So many students (A & B included) don't connect the concept that you make your car go faster by increasing its acceleration (hence, the correct name of that pedal, the accelerator). Or that when you pedal your bike faster, you are increasing the acceleration on the bike. They don't get that the new increased speed is the result of a rebalance of the new acceleration and drag forces. They memorize F=ma, but don't actually know what it means. It is one of the toughest things to overcome -- learning that your instincts are wrong. This is true in the physics classroom, and this is true in golf. Higher speed is the result of increased acceleration, and longer drives are the rest of not using your hands, etc. You have to fight to overcome your first instincts of how position, velocity, and acceleration are related in physics and your first hit instincts in golf."
The faulty conceptualization is the notion that there IS an acceleration at Time 1 and then an increase in (this existing) acceleration to get to a faster speed at Time 2. There is not. At Time 1, when the speed is steady, there is NO FORCE and NO ACCELERATION. A "balance" of forces means there is "no net force" in any specific direction and therefore no acceleration and no change in velocity. That's the case at Time 1 for anything moving at a steady velocity -- no "net force". That's the problem in your first two sentences above.
The sentence "They don't get that the new increased speed is the result of a rebalance of the new acceleration and drag forces." implies that the acceleration is still hanging around. It's not. If there were still a Force causing any change in velocity, the velocity will continue changing as long as the force persists. That's why 1g force applied to a rocket ship will eventually accelerate the rocket ship to the speed of light.
t = [v(final) - v(initial)] / g
How long does it take a rocket ship experiencing 1g to increase velocity from zero to the speed of light? The speed of light is 186,282.397 miles per second, which is 983,307,056.16 feet per second (ft/sec). The "force" of gravity on earth gives any and all masses (1g) acceleration for free-fall at the rate of 32 feet per second each second (32 ft/sec^2). So the equation above becomes:
This number of seconds is 355.65 days. So applying 1g "force" to the back of a rocket ship in space will accelerate the rocket ship from 0 miles per hour to the speed of light 186,282.397 miles per second (or 670,616,629.2 miles per hour) so long as the force is applied and the acceleration rate stays CONSTANT for nearly a year. How much "force" is exactly needed depends upon the "mass" of the rocket ship. F=ma. To get a = 1g for a 1-ton rocket ship (2,000 lbs or 907.18474 kg of mass), F = 907.18474 kg * 9.8 m/s^2 = 8,890.4 Newtons of "force". This is the same as 1,998.5 pounds, about like the "force" that a 2,000 pound ball of iron exerts on a person's toe when it rolls on top of their foot. That much "force" applied for nearly a year will accelerate a 1-ton rocket ship to the speed of light in empty space. (I know that in Special Relativity, this description is not accurate, since a mass at a velocity near the speed of light grows "more massive", and this requires greater and greater "force" to approach closer and closer to the limit speed of light, but in "our world" the description is accurate enough for describing how 'force" and "acceleration" work together on objects.)
If you STOP or REMOVE the force early at any specific time during that 355 days, the rocket ship simply STAYS at whatever velocity it then has attained. For example, if the force at the back of the rocket ceases after 30 days or 2,592,000 seconds, the velocity of the rocket ship at that time is v = gt, or v = 32 ft/sec^2 * 2,592,000 sec, or v = 82,944,000 ft/sec (same as 15,709.09 miles/sec or 56,552,727.27 miles per hour). But for all time thereafter, the rocket ship will REMAIN at this velocity forever so long as it moves thru empty space. No change in velocity means no acceleration. So once the force ceases, the acceleration disappears (becomes zero).
Your most recent language still has this faulty conceptualization of the acceleration hanging around with a given velocity. It doesn't. Any steady velocity has ZERO acceleration. You write, however:
"And, now that we know the force the engine has to be generating, and recalling that F=ma, we find the new acceleration the engine must be producing to achieve the newer speed. The acceleration needed to achieve v_2>v_1 is greater than the previous acceleration a_2>a_1."
Your term "producing" implies the acceleration stays around or else the "new [constant] speed" will drop off. That's not a correct way to conceive the physics. You also incorrectly think that the acceleration that got the car to velocity 1 must be SMALLER than the acceleration that increases the speed from velocity 1 to the faster velocity 2. Not true. An astronaut floating in outer space with a can of aerosol hair spray will accelerate from floating "motionless" beside the rocket ship to floating away at 1 mph after a single two-second blast of the hair spray. Then he will float away at 1 mph forever. One week later, while floating deeper into space at 1 mph, the astronaut gives a second blast of hair spray for another two-second pulse and he speeds up from 1 mph to 2 mph, and then floats away forever thereafter at 2 mph. The acceleration RATES are the same going from 0 to 1 mph and from 1 mph to the greater velocity of 2 mph. The acceleration used to get from 1 to 2 mph is NOT GREATER THAN the acceleration used to get from 0 to 1 mph. Now, going 2 mph, the astronaut gives merely a ONE-second blast of hair spray. He now increases speed from 2 mph to 2.5 mph. He went from a lesser speed to a greater speed but he did so with LESS acceleration than he used to get to 2 mph. In your view, ANY acceleration that gets a moving object from velocity 1 to a faster velocity 2 must ALWAYS BE GREATER than the acceleration that sped up the object from velocity 0 to velocity 1. That's simply "wrong", as in "not really the case anywhere in the known universe."
You write: "Thusly, my statement is correct -- in order to achieve a higher velocity, you have to increase the acceleration of the car, because the increased acceleration is the increase in force the engine puts out which determines the velocity that balances the new engine force with the drag force."
Your concept is that acceleration 1 "goes with" (stays with, exists alongside of, simultaneously accompanies and is necessary to, is an essential ingredient or component of) velocity 1 and to get the car to velocity 2, you simply INCREASE acceleration 1 to acceleration 2. But the truth is that when the car is going velocity 1, there is NO ACCELERATION. Your balancing concept of engine force versus drag force is a perfect example of "naive physics" getting it wrong.
Aristotle's view that heavy objects inherently tend to come to rest and that once a force ceases, the object will stop moving, is based on the premise that "every motion has a cause", but this was eventually modified by medieval thinkers to the notion of "impulse" by which an agent of force "impresses" into an object a magnitude of force that persists therein until resistance wears the impulse down. Most people blend the Aristotelian and medieval notions:
"For some students, the effect of a force may not appear at the instant it is applied, or the effect may be self-consuming or dissipated by external
resistances:
"The force does act only after...it overcomes the initial velocity."
"This force cannot stay forever...Nothing stays forever."
"The cannon has enough force to take [a cannonball] only that far."
"The force decreases...because of the pull of gravity in that [opposite]
direction."
Your discussion uses "drag" and "balancing" with these implicit misconceptions about the nature of force and the acceleration it causes -- a blend of the notion that with the engine off the car will "naturally" stop and that only with the engine pressing acceleration steadily into the car can the car maintain a steady velocity. Velocity in itself is NOT caused by anything. In physics, an object moving at 10 mph is not different in kind from an object moving at 30 mph or at rest, but IS different in kind from an object that is undergoing a FORCE that accelerates its velocity. But once the force is no longer active, the velocity does not change any more. Nothing "causes" a moving object to "maintain" its current velocity -- that's the "weird" thing in physics that humans just don't seem to accept when they try to "cipher" it all out.
Aristotle made the same mistake with his ideas of resistance:
"Aristotle discussed the resistance of a medium in detail and inferred that the speed is inversely proportional to the resistance R, which depends on the size and shape of the body as well as the density of the medium. Thus in an appropriate system of units (which Aristotle never discusses), Aristotle's law of falling bodies can be written as v = W/R." (From I. Halloun and D. Hestenes, Common Sense Concepts about Motion, Am. J. Phys. 53, 1056-1065 (1985), accessed 04/29/09. ) That's the same thing you are doing with "drag": the car velocity depends on the "balance" or ratio of engine "force" to drag "force". (You also confuse the concepts of "work" and "force" -- the engine performs mechanical "work" by moving a mass against drag a certain distance, and the engine expresses "power" by doing X amount of "work" in a certain amount of time. For example, a horsepower is equal to 550 ft lb/s, so to move a 2,000 lb car at 35 mph or 51.5 ft/s requires 187 horsepower to shove a motionless car 51.5 feet in just one second (102,900 ft lbs/s). A "horsepower" will move one pound 550 feet in one second or, the same, will move 550 pounds just 1 foot in one second.)
NASCAR teams test the aerodynamic designs of their car (to reduce oppositional "drag") at the GM and DaimlerChrysler proving facilities in Arizona, using a "straight-line" test as follows:
"In general a proving grounds site will cover several thousand secured acres, with multiple asphalt layouts and test tracks. The GM Desert Proving Grounds, for example, covers nearly 5,000 acres, while the DaimlerChrysler Arizona Proving Grounds is approximately 5,400 acres.
The GM and Ford facilities both contain 5-mile, banked ovals with long straightaways and wide, sweeping turns. DaimlerChrysler's site has 10 major facilities, including a 4.2-mile oval, a 2.4-mile straightaway, and an 18-acre skid pad at the site's Vehicle Dynamics Facility (VDF).
Teams typically use the straightaways to perform straight-line tests, which are either coast-down tests or downforce tests. In a coast-down test, the test driver will get the car to a certain speed-200 mph, for example-then clutch the car or take it out of gear. With the car coasting, engineers will measure the time and distance it takes for the car to get to another predetermined speed-50 mph, for example. Drag is then calculated using the measurements obtained."
(Jerry Boone, Stock Car Aerodynamics - Bad Air?, StockCarRacing.com, p3, accessed 04/29/09.) This is the same as "cutting the engine off" to see the effect of drag. Once drag is removed entirely (as in outer space), cutting the engine off results in NO DECREASE IN VELOCITY. The velocity at the moment the engine is cut off simply CONTINUES FOREVER, and there is no "cause" required to "keep" the speed up, ever. Ever.
"Drag is the major obstacle to acceleration and racing speed. A passenger car driving on the highway spends an estimated 60 percent of its energy overcoming air drag, a far greater percentage than tire friction and the energy needs of the drive train itself."
"For highway driving conditions, it is estimated that driveline uses about 15% of the total energy to required to push your vehicle down the highway, tire rolling resistance represents about 25%, and air drag is about 60%!"
Perhaps a better example to help clarify the "common sense" earth-bound figuring out of all this is to consider how a fan aimed straight up gives a stream of vertical wind that keeps a ping pong ball steady at a given height against the CONSTANTLY APPLIED downward force of gravity. The wind also has to be CONSTANTLY APPLIED, but when the opposing forces "balance", there is "no net force" and hence the ball stays in one place (has zero velocity and zero acceleration). There is NO DRAG either, since the ball has to be moving to experience drag, and it's not moving. INCREASING the "force" of the wind a notch by turning up the fan will do what?
a) move the ball at a steady velocity to a higher height where it again stops;
b) move the ball with changing velocity to a higher height where it again stops;
c) start the ball rising at a steady velocity without ever stopping;
d) start the ball accelerating upward faster and faster without ever stopping.
What actually happens is that as the ball gets farther from the fan, the speed of the wind on the back of the ball diminishes (the stream is opposed by other motionless air in the way) and hence the FORCE of the wind against the ball diminishes, so the ball rises and slows, and as it moves drag also comes into the picture, so the ball rises with changing velocity but again stops at a higher height. Okay, so let's put the fan on the back of the ball like a propeller. Now what happens when you turn the velocity of the propeller up? The added FORCE from the increased propeller velocity will:
a) move the ball at a steady velocity to a higher height where it again stops;
b) move the ball with changing velocity to a higher height where it again stops;
c) start the ball rising at a steady velocity without ever stopping;
d) start the ball accelerating upward faster and faster without ever stopping.
In this case, the ball will not do either of the above, but will start accelerating from motionless to faster velocity but drag will also start to increase, so eventually the ball will settle down to a TOP velocity but will keep moving so long as the propeller stays turning at this same velocity. A skydiver free-falling from 10,000 feet will not accelerate steadily faster and faster until he hits the ground, because DRAG will result in the free-fall stalling out at a "terminal velocity" that is plenty fast, but the skydiver won't get going faster than this as he continues to fall. This terminal velocity is about 200 km/h or 124 mph. (Speed of a Skydiver (Terminal Velocity), The Physics Factbook, Hypertextbook.com.)
"A free-falling object achieves its terminal velocity when the downward force of gravity (Fg) equals the upward force of drag (Fd). This causes the net force on the object to be zero, resulting in an acceleration of zero." (Terminal Velocity, Wikipedia.com, accessed 04/29/09.) In the other direction, moving against air resistance along a highway, the drag opposes the forward motion, and, as you say, INCREASES with increasing velocity. But it is NOT "Force" from the engine that overcomes the drag; instead, it is POWER (force performing a given amount of work in a given amount of time, or the rate of doing work).
"The power needed to push an object through a fluid [or the gas of air] increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power." (Drag, Wikipedia.com, accessed 04/29/09.)
All of this "drag" business obscures and confuses the reality of the physics of force, mass and acceleration. This confusion is why Galileo and Newton both had to conceive the physics WITHOUT the drag or wind resistance or friction on earth mucking up the clarity of the physics, and this INABILITY of most humans to think like that generates "naive physics" of faulty conceptualizations of what is happening in reality.
What difference does it make in golf? It usually means the golfer "thinks" about "how hard to hit the ball" or "how fast to hit the ball" or that he needs to "increase the acceleration" of the putter thru impact to "avoid deceleration. Golfers typical misunderstand the difference between "force" and "momentum". Almost everyone does NOT get the difference between "mass" and "weight". Nearly everyone believes that the heavier object falls "faster" and therefore arrives at the bottom of a pendulum swing going "faster" than a lighter object swinging on the same radius. Nearly everyone thinks that a larger backstroke takes longer to cover the distance down to the bottom of the pendular arc than a shorter backstroke with the putter head beginning "closer" to the bottom. Golfers very nearly ALWAYS misconceive the relative influences of air resistance, green surface friction, and gravity sideways torquing of a putted ball rolling across a contoured green. Golfers have very faulty concepts of what "true roll" means, how to generate it, and what difference it makes for putts, putters, and stroke motions. Golfers and indeed supposed golf "scientists" usually confuse the relationship between potential and kinetic energy in a pendular stroke with the "force" that results from the "momentum" of the putter head impacting the ball and mistakenly believe that the energy cannot possibly be sufficient to roll a ball very far, since the putter height at the top of the backstroke is not high enough to correspond to much energy. This in turn leads these supposed experts to state that increasing acceleration and TORQUING the stroke MUST be required to get the desired level of energy, and that a natural pendular stroke CANNOT POSSIBLY generate enough force for usual putts -- all of which is incorrect. It sometimes results in golfers thinking there is a magic spot in a breaking putt where "gravity will take over and move the ball downhill the rest of the way to the hole so all the golfer needs to do is get the ball to that spot" and other nonsense like that. (What was gravity doing before that magic point -- waiting secretly in the bushes?) The basic idea that putts always travel uphill before "breaking downhill" back to the hole is incorrect in itself -- breaking putts travel "away" from a straight line between ball and hole and then travel back "towards" this line and the hole at the end of this line, but many breaking putts never result in the ball being "uphill" with the hole "downhill" beneath it -- the hole is "uphill" above the ball all the way until the ball drops over the lip. Plenty of putts are "downhill all the way", so the ball at address is presumably already at that magic point, so just tapping the ball to get it moving the least sped possible is all that should be required, but it usually isn't and this only works when the slope and green speed combine so that NO BALL WILL STOP ONCE STARTED. So that's all a very limited and limiting way to approach the issue. The misconceptions in the physics of body motion are too numerous to catalog. These misconceptions pop up all the time in golfers' thinking about what is going on and what they need to do to make things work out.
What do you think happens in a pendulum putting swing? Do you think the putter head has increasing acceleration into impact? If you think it is accelerating, that is correct, but if you think the acceleration is increasing, that is incorrect. And if you also think that the acceleration is at least NOT decreasing, that also is incorrect. The acceleration in a clock's pendulum DISAPPEARS completely right at the bottom of the stroke. Right at the bottom, the acceleration is ZERO. Before the bottom, the acceleration is DECREASING (but still positive). After the bottom, the acceleration goes from ZERO into negative, and gets more and more negative as the swing continues. If you think at the start of the downstroke from the top of the backstroke that the acceleration is INCREASING, that is incorrect. The acceleration at that point is maximum but immediately starts to diminish.
In general, people get very confused when they try to conceptualize velocity and acceleration, as you exhibit. Velocity is change of position over time and acceleration is the RATE of CHANGE (increase or decrease) of the velocity. No change in velocity, no acceleration; no acceleration, no force; any steady velocity has ZERO net force and ZERO acceleration. Any application of force to a steady velocity object imparts an acceleration from velocity X to velocity Y, but neither the force nor the acceleration need "hang around" and neither becomes "welded into" the velocity and neither is required to keep being applied to keep the velocity at the same level, as long as nothing opposes the motion of the object to slow it down.
In your drag versus engine "balancing", you confuse velocity and acceleration and also have vague and confused times that are being talked about. The drag you talk about is a CONSTANTLY APPLIED FORCE in opposition, and so must be met by the CONSTANT APPLICATION of the countering engine force. If these forces were visualized as opposing diminoes walking straight at each other meeting at a scrimmage line, one domino per slice of time, there is one white drag domino met by one black engine domino and then there is a second black engine domino like a halfback following a blocker. At each moment, the second force does its thing and disappears and the acceleration gets the car from zero to 35 mph. The acceleration RATE is not an increase over a preexisting acceleration, since there wasn't one until the halfback domino made it past the scrimmage line. Once the second black domino force has been applied, the force disappears. Then a second slice of time occurs with three other dominoes. And this keeps the car at 35 mph. That's all complicated but its not a good way to think about physics so that the reality becomes clear.
Surely you've seen the space movies where the space-walking astronauts accidentally "drops" the screwdriver and it floats away forever. If the astronaut shoved the screwdriver away towards the SUN, the screwdriver would speed up to velocity X (say, 10 mph) and then continue coasting along at this "cruise speed" forever or until it actually hit the SUN. No change in velocity once the force stops acting. At 10 mph for the rest of the trip of the screwdriver, there is no force and zero acceleration.
Steady velocity with no CHANGE in velocity, no acceleration. NO acceleration, no force. No force, no change in velocity. No change in velocity, no force.
Basically, if you depress a gas pedal 2 inches and then keep it depressed at that level, the car will get faster and faster and faster and faster and faster etc. Ignoring drag, if you get the car to 60 mph on a flat road without weight and friction and air resistance and drag, and then cut the engine off, the car will STAY at 60 mph indefinitely.
Naive physics are born out of a "common sense" wrestling to speak about what happens on earth, and this is the problem. Physics has to be conceptualized without the colored lenses of the earth-only experiences in order to get the concept correct. And then the language is not goofy.
Once the concepts get corrected, and the language goofiness subsides, THEN the person can actually learn and think and understand. But don't for a second think your explanations are free of naive physics misconceptions and goofy language. It's just human nature to do what you do. But it's not a good thing -- it's just a workable solution MOST of the time, but unfortunately not usually a workable approach for understanding sports movements and teaching and learning them.
Golf instructors who either a) cannot explain how a body skill works in terms of accurate cause and effect, or b) use odd language with embedded misconceptions of naive physics or weird anatomical or biomechanical notions as if this doesn't matter and as if clarity of understanding and teaching is not really required are not helpful in the long run. In the long run, this is a major problem that needs fixing in golf.
Geoff: "Golf instructors who either a) cannot explain how a body skill works in terms of accurate cause and effect, or b) use odd language with embedded misconceptions of naive physics or weird anatomical or biomechanical notions as if this doesn't matter and as if clarity of understanding and teaching is not really required are not helpful in the long run. In the long run, this is a major problem that needs fixing in golf.'
..................
Apart from yourself, can you name several golf instructors who approach these criteria?
It seems to me that the golf instructors over the last say 5 decades were only attempting to 'sculpt' golfers rather than 'build' golfers. The new batch of golf pros coming out of the colleges and universities seem to show a steady advancement, but the average recreational golfer is still quite incompetent. Perhaps people don't really want to learn anything much about golf and prefer to puddle about ....
What are your thoughts on a scratch or +1 golfer who has taken limited lessong in their life really knows nothing about their swing or swing mechanics, what Geoff has to say about putting but simply goes out and shoots 70-76 on any course on a pretty consistent basis?
or
a musician who knows nothing about music theory or how to read music but can play just about any instrument put in their hands. Can play any song they hear and can tear it up on the piano and guitar?
or a painter that can paint incredible painting of anything. Nature, people, animals etc. but knows nothing about art, art history, artist etc.?
Please allow me to respond to this, even though you have addressed sammy specifically, as I have a constant patter I give out on this very subjects and perhaps you will comment on my patter helpfully.
The PGA Tour is crowded with human "freaks" who can do certain things with golf clubs that hardly anyone else can do, in the space of problems posed by different golf courses by tee boxes, fairways, rough, hazards, bunkers, and greens. The fact that these individuals do not know how or why they are as good as they are does not mean they will necessarily get harmed by trying to know or that they cannot get better or more consistent if they understood more about their gifts or talents.
Yes, it is a problem of knowing how to try to help someone at that level of play without derailing their natural successes, but it is not impossible. I hope and believe that my approach to understanding and enhancing innate natural brain processes for perception and movement common to all normal adult humans, including golf stars, accomplishes two important goals without conflicting with natural gifts: 1) make the gifts stronger and better, and 2) make the gifts more consistent.
The fact is that gifted golfers are not the best models for understanding, learning or teaching golf. Ben Crenshaw warns golfers that his putting style is probably not best for them; Jim Furyk won't change his idiosyncratic full-swing and no one teachers golfers that this is a good swing for them; the more gifted the player, the less important specific technique might be required for their current higher-than-you level of performance but this does not mean better technique would harm the gifted golfer or trample on something he needs that he doesn't know how to describe.
There are at least two categories of golfers: those interested in playing the game better for whatever reason, and those who play in competition to win by beating whoever shows up by at least one stroke. Invariably, the golf community regards competitive golfers as the "best", but they do not really have excellent technique as the main goal (some more than others). Bobby Locke, Gay Brewer, Jerry Barber, and many others had sub-standard technique but could SCORE and BEAT others. Walter Hagen was the match-play champ par excellence, and trounced Bobby Jones in match play when Jones was at the height of his skill and Hagen was in his twilight years. Lee Trevino has always been the master of doing it his way. Sometimes these stars have technique that transfers well to the general population of golfers, because it is relatively free of dependence upon the idiosyncratic gifts of the star and based nearly entirely on sound fundamentals applicable to all normal adult humans. That's why golf instruction articles and books by great players vacillate between the two basic presentations: 1) this works for me for some reason so I recommend you give it a try and see if it works for you, too; and 2) this is the way you should play if you want to be as good as I am.
When great players try to share what makes them great, they always run up on this fork in the road about which way to present their techniques. The golf magazines want the players to "model" technique so golfers worldwide will have hope of duplicating great performance, so there is an implicit discouragement of players simply presenting their idiosyncratic technique as solely for them for some unknown reason. Golf teachers talking about Jim Furyk's swing, for example, always focus upon how he "returns the clubface thru impact" so well, and salvage this aspect of his technique for the "model". But they don't really "model" HOW Jim gets this done and what's good or bad about that for the general golfer. Golf magazine presentations of "tips" by players are almost always just recycled "standards" from the great dustbin of golfing lore, where junk accumulates decade after decade without a collective critical intelligence. So Tiger Woods teaches in one tip how he "sets his eyes above the ball" so he can "see the line" in putting -- he actually does not do this personally, and in the tip in Golf Digest what he models is not the correct lore anyway (as taught in the 1960s, he leaves out half of the technique that makes it workable), and what he models clearly does not do what he says it does for him or for anyone else. So how does that get printed?
When golf greats attempt to transition from the basic truth of "this works for me for some reason" to "this is the way you should play", sometimes the EXPLANATION makes sense, but usually it does not. For example, when a putting teacher says "hit down on the back of the ball", and THEN explains why this is generally sound for all normal adult golfers, he starts making a mess. Similarly, when a putting teacher says "swivel your shoulders only in a horizontal way" when you putt, and THEN starts explaining the anatomy and biomechanics that supposedly makes this a sound technique for all normal golfers, he makes a right royal lot of nonsense with odd justifications and queer anatomy. When a putting teacher says all golfers should positions their hands directly below their shoulders or else their stroke will have a curved shape, he speaks drivel that is completely uninformed by the realities of robots AND humans, since any little experiment will show that hand position is irrelevant to making a straight stroke so long as the structure of the body from shoulders to putter head does not change in the making of the stroke, regardless of where the heck the hands might be (as is always the case with putting "robots" like Perfy or Iron Archie). If putting teachers are making a mess of this, you know a competitive golfer who does not have enough time to think clearly about the issue is also likely to make a mess of it when justifying a given personal technique to the general golfer, and they usually do.
Golf lore comes with stamps of previous acceptance. The "reverse overlap grip" has a) the way to do it, and b) the explanation "why" it is sound and good for all normal adult golfers. As to b), there is a repository of previously "vetted" explanations any player can simply "stick on" and golfers will accept it. For the "reverse overlap grip", the player justifying this in the magazine says: "It prevents left-wrist breakdown" or "It solidifies my hands so they operate as a unit" and similar tripe. The truth is that the "reverse overlap grip" entered golf sometime before 1900 as a "bandaid" for bad golfers on bad greens with bad putters and has been around ever since. Top players today are not bad, the greens are great, and putters are designed to the hilt, and these players NEVER flip their wrists in the putting stroke, and there are better grips to use. So why do they "stick" with this grip and why do they spout the same old previously accepted justifications to encourage other golfers to do as they do? it's just golf culture. A more reasonable approach would be to address directly why golfers might be flipping their wrists thru impact and cure that, rather than bandaid it so it becomes a permanent threat that is fought to keep under wraps. Golfers flip their wrists because they stop their shoulders while their arms and hands keep a-flyin', and this happens because they don't know how to control distance with a calmer, less violent form of stroke motion. Teaching a "reverse overlap grip" is not getting to the root problem at all. Top players get past this root problem and don't need a "reverse overlap grip", but they don't really know this. So they are not "models" and when they act like models, their justifications are almost always just picked out of the dustbin and stuck on for persuasiveness.
Anyone who actually reads all the putting books and all the putting magazine articles will undoubtedly be struck by just how little originality or actual insight gets communicated through the decades of golf instruction. A really, really valuable book on putting by a really great golfer MAY contain 3-5 original insights, tops. The self-motivated learner would probably be better served dipping in and out of a kitchen-sink style book of putting instruction like the "Arnold Palmer's Complete Book of Putting" (written almost if not entirely by British golf writer Peter Dobereiner), where the learner can read discussions of just about everything ever tried in a big jumble of a book, the basic message of which is try to be less conscious when you putt. The truly valuable books by players are the ones that don't stray far past the starkly honest presentation of "this is what I do and it seems to work for me, and maybe this is why but I'm not sure but here's my opinion to consider". That's Dave Stockton Jr. and Bernhard Langer's and Jack Nicklaus' books -- great detail about what they do very honestly and simply presented, some with "justifications / explanations" and some without. (Nicklaus frankly admits he doesn't understand putting, that it's a mystery, and so far as he can tell "There are no rules" for a competitive player" although he vest in fundamentals instead of "feel".) Ultimately, the learner / teacher has to sort out what works and why regardless of the explanations offered by others. You don't really want to be saying "try this, I don't understand it but it might work" unless you have no other option.
Frankly, seeing the same justifications repeated all the time from the dustbin without careful analysis and unconnected to honest discussion of what exactly a given player really does personally gets to be quite a chore. You basically learn to mark the "lore" as "slice and dice" crappola that relates only to one little aspect of putting without connecting up to an integrated set of skills. Advice like "put the weight more on the left foot in the setup" because "blah blah crappola crappolla crappolla ..." and "put your eyes over the ball" because "blah blah crappola crappolla crappolla ..." or "stand taller in the setup" because "blah blah crappola crappolla crappolla ..." and "putters need at least 3 degrees of loft" because "blah blah crappola crappolla crappolla ..." and "hit down on the back of the ball" because "blah blah crappola crappolla crappolla ..." and "the backstroke should be short and quick" because "blah blah crappola crappolla crappolla ..." eventually strike the person familiar with the full gamut of golf lore as a sign that the person presenting the advice hasn't really thought about or even experimented all that much with what they suggest for you. Eventually, the self-motivated learner says "a plague on all your houses" because this is very NOT helpful, and now I have to start from scratch and figure everything out from first principles concerning physics, the equipment and course, and the human moving/perceiving body. At this point, honest and accurately described insights become worth their weight in gold.
So, in the United States at least where golf magazines and broadcast media have a large and undue influence on what sort of teaching is accepted, top players are not the best "models" for understanding, teaching, or learning golf fundamentals. They are out to win, and that is priority number one, with sound technique applicable to all other golfers a distant second priority. They aren't the best "understanders" of why their technique works or whether it applies to the general population. And they are often good performers because they are somewhat "freaky" in their brains and bodies, unusually suited to do well the skills demanded in golf, and this makes specific, fundamentally sound techniques less required than otherwise -- not a good thing generally.
I think we are saying the same thing, but you are using the concept of net force and I am looking at a specific force.
You are correct in saying "A car that is going at a constant velocity has NO FORCE making it go faster (or slower). " if you include the word "net" in there like:
A car that is going at a constant velocity has NO NET FORCE making it go faster (or slower).
And that I completely agree with.
But, the reason there is no net force, is because F_drag = F_engine, or equivalently F_drag - F_engine = 0.
If you look at the specific forces, F_engine, if you want your car to maintain a constant speed that is greater than it's current speed, you have to increase F_engine such that F_engine_new - F_drag_new = 0, and that greater speed is the speed which makes F_drag_new equal to F_engine.
Just as another example: "Acceleration does not "hang around" after the force has been applied. And the force does not either." becomes much more agreeable (to me, anyway) if you include the word net in there a few times:
Net acceleration does not "hang around" after the net force has been applied. And the net force does not either.
Because, a moving at a steady speed certainly does experience forces (drag being the biggie)! And, I don't think that you are saying it doesn't, because the drag force and the engine force are ever present, they just exactly nullify each other.
Like I said, I think that we are saying the exact same thing, but you are talking about net forces, and I am talking about 1 specific force that goes into the force balance.
This message has been edited by notBignose from IP address 65.101.164.66 on Apr 29, 2009 8:51 PM
Yes, you are right about "net" forces, and I am not trying to argue with you about how cars get thru the air drag (although that is very interesting). My main point is that understanding, teaching, and LEARNING human movements for golf (specifically, putting) requires some precision in the language of thought and communication. This is not a "whatever floats your boat" issue. there are serious consequences of using language in thinking about and talking about the basic physics, anatomy, and biomechanics when the language is vague or confused or confusing about the fundamental reality being addressed (whether it is the acceleration pattern, the transfer of momentum, the pattern of muscle recruitment, or what the skeletal structure does or does not have to do with good motion, etc.).
Nor do I mean to imply that getting this language correct is an easy task, such that golfers who don't use well-considered language must be "stupid" or "lazy". It's clearly not the easiest thing to do, as University physics students don't usually come close, and Galileo had to correct Aristotle when for 2,000 years everyone thought he had it right ("heavy objects fall faster than light objects") when he clearly was wrong if anyone cared to check the facts with a really stupid experiment (just try it and see whether a heavy thing drops faster than a light thing -- say, a golf ball and a ping pong ball without wind or a quarter and a dime -- it doesn't and never has or will). But I do say that a serious golf teacher better give it a serious try, and even a very highly reputed golf teacher or student or player who does NOT try to get this fog of golf-speak sorted out and clarified in alignment with reality will definitely limit his ability as teacher, learner, or performer.
I've been told I should tone it down about specific others, which may indeed be true. (I like to think I confine my critical remarks to WHAT someone teaches, but in many cases I'm sure I let the talk slop over a bit into by talking about why the person's ideas are faulty and this sometimes leads to remarks that sound more like personal criticisms -- not good.) My general approach has been to make myself available on a friendly basis for a long while to other teachers first, and have done this in all cases by initiating direct, friendly contact and inviting conversation and mutually beneficial communication if not collaboration. No one who considers himself primarily a prominent putting instructor ever contacts me or takes the initiative or seeks to engage me in dialog. That's golf culture. After a certain number or attempts, I have no reason to expect the person wants to communicate. Pity, but that's the culture. Let's just say that I have had the same experience Boo Weekley had the first year he had his card on Tour and went up and down the driving range saying hello to all the potential "new friends" he saw.
I'll tell you exactly what it is and I'm sure you know this. Let's take a guy like Stan for example. For the most part, for some unknown reason he has fallen into a position of being known as a great putting instructor on tour. In a fairly short amount of time he has had more guys come to him seeking his knowledge then he ever could have imagined. And in return it has put a big new wind into his deflating golfing sails. To be honest where would Stan be without the putting guru status? As we know from his scores and stats certainly not tearing it up on tour. Hell he struggles on the Nationwide when he plays-if he still does. So, the last thing he wants to risk is befriending you, finding out he really knows nothing and in the process seeing all of his students flock to you. He would in essence give you the street cred that is required to get into the small clique type atmosphere on the tour. And he nor any of the others wants to make that risk. One that would not care about befriending you and tapping your knowledge and spreading your wisdom would be Peter Kostis. I think Peter is confident enough in his abilities and his thurst to gain as much golf knowledge as possible will overide anything else.
