Importance of Acceleration Thru Impact - Page 3

There is no acceleration through impact, although that should always be the intent.
 

The club head and ball impart an equal force on each other at impact and the club head is actually slowed down by this process and will not regain any speed lost.

But does catching up with hands mean maximum speed? Cause on Rory's graph his arms are slowing down substantially, while the clubhead is still gaining speed. Which means, the hands are ahead of the clubhead at impact, and the hands are slowing down. Its only logical that the clubhead catches up, ITS MOVING FASTER. Its like giving you a 50 yard head start versus Usain Bolt. 
 

Assuming the maximum speed happens when the club is fully extended is wrong. If Rory was accelerating through impact, the graph would extend past impact by a lot more. But it doesn't it crests at or just before impact. This means, even if his hands are forward, the clubhead is reaching max speed before its fully released. 

I'm pretty sure tiger is thinking about the shot than Accelerate through the ball. He knows his impact position is going to promote the speed he wants. To think otherwise brings in factors that are beyond the scope of any shot. 

Quote:

Originally Posted by dereckbc 

OK Jamo you seem to be one of the more open minded Admin/Mods on this forum.Take a look at Tigers super slow mo with a 6 iron and note how far ahead his hands are at impact. There is is only 1 physical way to do that. This is HD Super Slo Mo stop action film. No distortion. The club head does not catch up to his hand until about 6 inches past the ball. Put another way the shaft and left arm do not form a straight line until well past the ball. There is no doubt about it. He accelerated through the ball.

Catching up with hands doesn't necessarily mean maximum speed. Also, that swing is Tiger hitting a "stinger", not a normal shot, which is why his hands are so far forward

Quote:

Originally Posted by dereckbc 

Ever seen George Foreman or Bruce Lee throw a 3-inch knock out jab before? Do you really think they quit at impact, or followed through the punch driving with everything they have at the opponent to the ground?

I'm agreeing with the fact that they are in fact accelerating through the punch....but the fact is that when the punch meets resistance ( the boxer's head) energy begins to be transferred and therefore the net effect is a loss of speed because it was transferred in to the boxer's head. 

Just like those steel balls that swing back and forth. The ball is accelerating into impact with the other one...but when they meet the ball that initiated the contact stopped dead in it's tracks because it transferred all of it's energy to the receiving ball.  Had this other ball not been in the way then it would have continued on it's arch otherwise. This would be more like a golfer hitting an impact bag versus taking a full rehearsal practice swing. Example other than a golf helped me understand what I think the guys are trying to say but I am just giving examples.  The energy may have been accelerating...but it can no longer accelerate if it meets resistance...ie  golf ball or the turf.   

Excellent read from both points of view

http://www.tutelman.com/golf/swing/accelerateThru.php

Quote:

Originally Posted by dereckbc 

I respectively disagree and so do physics and the major majority of instructors.

Then the majority of instructors are wrong. It wouldn't be the first time - the "majority of instructors" STILL don't know the ball flight laws.

Fortunately for us the laws of physics don't care how people vote.

Also, "physics" agrees with me. Talk to a physicist or a guy who has a background in the sciences. Like me. 

Now, in the past some have taken my responses to things like this to be more aggressive than they think is necessary, but from where I'm sitting, I know beyond a shadow of a doubt that you're wrong. This isn't opinion, it's the realm of science and fact, and I take the education people get on my forum very seriously. I want them to get the BEST information, and the CORRECT information. So I speak unequivocally.

You are wrong. Let's explore more of the reasons why:

Quote:

Originally Posted by dereckbc 

Using the thought you imply is a guaranteed method to promote casting the club and coming over the top.

Oh brother. FWIW I was giving you an out by saying that perhaps some people might like to FEEL or THINK they accelerate the clubhead THROUGH impact, because I've been clear in saying that they don't actually want to do that. Feel ain't real.

(Snipped out parts where you try to put words into my mouth, etc. Please, don't do that.)

Quote:

Originally Posted by dereckbc 

The human brain and body is not capable of timing what you suggest.

 

What timing have I suggested? I haven't.

 

I have simply said that the best golfers reach maximum clubhead speed AT the ball. To do so AFTER the ball would be to waste speed. It's a pretty simple concept. Thousands of great golfers reach maximum speed within an inch or so of impact. Clearly the human brain and body are "capable" of doing just that.

 

Quote:

Originally Posted by dereckbc 

I certainly cannot even begin to teach that.

 

Uhm...?

Quote:

Originally Posted by dereckbc 

I certainly cannot even begin to teach that. What I can teach, and the brain/body can do is accelerate through the ball. It is very easily to visualize by cracking the WHIP just ahead of the ball, not at the ball as you suggest. The swing does not stop at impact.

 

Nobody's said it does. Furthermore, I've never said players hit "at" the ball or do any such thing as you want to keep claiming.

 

Read what I wrote. I'm discussing two things:

1) What ACTUALLY happens at impact (specifically among the game's best players).

2) What may be a "feel" that might work for someone.

 

I've spent the vast majority of my time talking about what ACTUALLY happens (#1 above).

 

 

Quote:

Originally Posted by dereckbc 

Notice the bend in the shaft and hands leading the club. There is only 1 physical way to do that: Accelerate through impact.

 

I could create that picture accelerating, decelerating, or maintaining a constant speed.

 

Again, so that I'm clear: the best golfers deliver the clubhead at maximum speed at the golf ball. Period.

 

I'm not making any claims as to HOW they do it, what they FEEL or THINK they're doing, etc. I'm talking about the pure physics of it. The clubhead does not accelerate AFTER impact in the game's best players. It reaches maximum speed just prior to or right at impact, then - because of the ball, good timing, the ground, etc. - the clubhead immediately decelerates.

 

Some low handicappers will have peak speed after impact (though only on teed balls - the ground tends to slow the clubhead down too much to recover). Many/most poor players will have peak speed well before impact. The best players have peak speed AT impact.

 

Very simple concept.

 

Quote:

Originally Posted by saevel25 

The idea you need to accelerate through a bunker shot is crap. Most people think Amateurs don't accelerate through a bunker shot, or give up on it, is false. Most of them over compensate for poor advice and throw off there whole timing. How many Amateurs do you see who chunk a bunker shot, why because they think, "i got to accelerate through the shot", and they release the clubhead way to soon, causing it to bottom out way before the ball. 

 

If you look at a tennis strike's kinetic chain, it has the same characteristics as a golf club. Hip rotation, coupled with torso rotation, up to the arm, then whipped through by the tennis racket, with acceleration of the racket being near zero at impact for MAXIMUM racket speed. 

 

Golf or Tennis, the kinetic chain for the club or racket is a Parabola, meaning that the maximum speed is when acceleration is ZERO. that is basic calculus. For hitting a golf ball or hitting a tennis ball, its speed that counts, not acceleration. 

saevel nails it.

Quote:

Originally Posted by dereckbc 

You just made my point. an early release is casting the club or throwing the club at the ball. Video evidence of good bunker players is over whelming proof because the club club passes the ball out of the trap.

That's not proof of much, particularly since the clubhead doesn't even touch the golf ball in a bunker shot. The sand is impacted, and the leading particles of sand aren't passed by the clubhead. Furthermore, the clubhead is traveling on a completely different path than the ball on a pitch shot (let's remove the sand), so yeah it can "catch up" because the ball, once struck, has only gravity and air (friction) to slow it down while the clubhead has a dude with muscles attached. If it's decelerating more slowly than gravity (but still decelerating) it could "catch up" to the ball - but again, we don't even see that happening, and any illusion of the clubhead "catching up" is because the ball is not traveling on the same path as the clubhead. The clubhead is traveling very flat (large lateral vector, i.e. forward) while the ball is traveling UP and its lateral vector is very small.

Quote:

Originally Posted by phillyk 

I think physics-wise, the difference between accelerating through impact and having no acceleration at impact are negligible for the speed the clubhead will have at impact.  The amount of energy put into the ball from the clubhead's mass and velocity will transfer to the mass and speed of the clubhead after impact, the amount of spin the ball will have, and the mass and velocity of the ball, minus some residual heat from the impact.  Based on some numbers I found on the web and from iacas's masses of the ball and clubhead, a rough calculation based purely on those parameters reduces the velocity, of the clubhead after impact, dramatically.  Now, the percentage of velocity lost if you were "accelerating through impact" versus making sure the velocity was maxed at impact is small.  In REALITY, the velocity at impact will be the highest throughout the whole swing. To make it FEEL better, the notion of saying to try and "accelerate through impact" might help players focus on swinging towards the target, even if they lose a small portion of the possible velocity.

Yup.

And the fact remains that if you actually somehow accelerated AFTER impact, that would be an INEFFICIENT swing because you'd be wasting "speed." Speed after impact is useless.

The ball's gone - do you want to have 100 MPH clubhead speed at impact and 110 MPH when the ball is ten yards down the fairway, or would you rather have 110 MPH clubhead speed at impact and 100 MPH when the ball's twelve yards down the fairway?

Quote:

Originally Posted by phillyk 

OK, i did another calculation for the difference in velocity, between the bottom of the swing with full velocity and an acceleration through impact velocity, with the following assumptions: the down swing starts with shaft parallel with ground, constant acceleration in the swing to max velocity (with other assumptions = about .072miles/s^2), a time of .4s for the downswing (to impact area), a man's arm length of 33", a driver shaft length of 44.5", the speed at the bottom of the swing is 100mph, and that an "acceleration through impact" would mean making the top speed appear at about 35° past the bottom of the swing.  I can do other quantities if you want me too.  To reach that 35° mark from the bottom of the swing takes .026sec making the velocity at that point 106.8mph, an added velocity of 6.8mph.  So, I guess it does make a bit of difference.

Your math doesn't shed any light on the subject. Again, who cares what your clubhead speed is after the ball is gone? If you're hitting the ball with 100 MPH and reaching 106.8 MPH after the ball's gone, you'd be better off toping out at 103 MPH at the golf ball than whatever you're doing to reach 106.8 35° after impact.

Quote:

Originally Posted by dereckbc 

You think? Try to put that swing thought in your head and hit at the ball and see what happens. Or you could do what the Pros do and KISS by just accelerating through the ball to the target. The secret is a constant and deliberate acceleration through impact. and crack the whip in front of the ball toward the target.

You said before that thinking about accelerating through impact will lead to casting and coming over the top, didn't you?

Pros accelerate TO impact, not THROUGH impact. Very plain to see, and well understood among the actual scientists who are involved with the game of golf. Talk to some of them.

Quote:

Originally Posted by dereckbc 

There is is only 1 physical way to do that.

No there isn't. You could arrive at that position, again, with positive or negative acceleration (deceleration) or a constant cruising speed.

Pros arrive at impact with their maximum speed. They're not accelerating after impact.

Quote:

Originally Posted by dereckbc 

He accelerated through the ball.

 

No he didn't (and saying it over and over again doesn't make it true).

Quote:

Originally Posted by saevel25 

Assuming the maximum speed happens when the club is fully extended is wrong. If Rory was accelerating through impact, the graph would extend past impact by a lot more. But it doesn't it crests at or just before impact. This means, even if his hands are forward, the clubhead is reaching max speed before its fully released. 

 

I'm pretty sure tiger is thinking about the shot than Accelerate through the ball. He knows his impact position is going to promote the speed he wants. To think otherwise brings in factors that are beyond the scope of any shot. 

Bingo. Several gold stars for saevel today.

Why would Rory want to reach maximum speed with his driver after the ball's gone? That wouldn't make any freaking sense! It would be inefficient. He'd be wasting energy.

The ball is not "compressed extra" if you're "accelerating" through impact... and you ain't accelerating through impact. Even if you were, DURING IMPACT the clubhead would be decelerating because it goes from swinging through the air to, you know, whacking a (relatively) heavy golf ball. It's not a cotton ball, after all.

Originally Posted by Lihu 

At first I thought at if you could put more dwell time on the club and ball impact that more energy is transferred and the velocity of the ball is increased due to the constant or even increasing force on it for a longer time. The flaw is that if the time does not increase, then this does not affect the ball velocity.

It doesn't. Impact lasts about 400 microseconds for almost every shot in golf, oddly.

Quote:

Originally Posted by Righty to Lefty 

I'm agreeing with the fact that they are in fact accelerating through the punch....but the fact is that when the punch meets resistance ( the boxer's head) energy begins to be transferred and therefore the net effect is a loss of speed because it was transferred in to the boxer's head.

I agree except for the fact that they're not doing that "in fact" - they're just feeling like they are.

Quote:

Originally Posted by Righty to Lefty 

Excellent read from both points of view

 

http://www.tutelman.com/golf/swing/accelerateThru.php

Iacas do you agree with this article where is says that the intent should be to accelerate the club through impact whether that is what happens or not, because if you don't then loss of torque during the swing does decelerate the club or cause the golfer to cast as he showed in the model.  I gathered that he was saying that it is not possible to maintain speed through impact because of the collision with the golf ball, but the intent to accelerate through impact is most likely to keep the proper torque on the club down and through impact. 

Quote:

Originally Posted by Righty to Lefty 

Iacas do you agree with this article where is says that the intent should be to accelerate the club through impact whether that is what happens or not, because if you don't then loss of torque during the swing does decelerate the club or cause the golfer to cast as he showed in the model.  I gathered that he was saying that it is not possible to maintain speed through impact because of the collision with the golf ball, but the intent to accelerate through impact is most likely to keep the proper torque on the club down and through impact. 

No. That's a "feel" or a "thought" that might not work for everyone. The article doesn't have the best physics, either.

Look, at impact, nothing you're doing with your hands on the grip end of the club have anything to do with the collision happening three or four feet away - the clubhead essentially acts, in all models, as if it's a free-floating body with about the last three or four inches of the shaft contributing weight but nothing else. The clubhead does not behave as if it is attached to anything - certainly not to your hands - at impact. You cannot "add" any extra force because of pressures or torques in your hands. If you could magically make all but the last 3" of the shaft (at the clubhead end) disappear the instant the face was an angstrom away from the ball, and only have it re-appear after the ball was completely off the clubface, nothing about the impact, ball flight, etc. would change. The ball and clubhead would behave identically because that's how they behave. Impact is too short for anything happening more than a few inches up the shaft to have any effect on impact.

Plus he's dead wrong about putting. The best putters in the world reach their maximum speed about one inch BEFORE impact and are actually decelerating slightly at impact.

Quote:

Originally Posted by jamo 

That's a gross misapplication of F=ma.

Yeah, that too. :)

Let me summarize once again what my position is.

The best players reach maximum speed at impact. It is the most efficient way to swing the golf club, as a clubhead that's decelerating or still accelerating is not hit with maximum speed - a decelerating clubhead reached it prior to impact, and an accelerating club reached it after impact. If the ball wasn't there, they might reach maximum speed an inch or two after impact (no more), but the ball makes it impossible to accelerate "through" impact.

If the thought of "accelerating through the hit" helps some players, I can see that. I don't personally recall ever teaching that feeling to someone, but that's not to say it can't work.

Well I always hated physics so I'll continue to FEEL what I need to do to get the shot to fly how I intend and try and learn the more in depth stuff as best I can then!!

I think, there needs to be a mention on what our muscles do during this time period, because that is responsible for the feeling behind "accelerating through impact."  Our muscles only provide the energy necessary to move the club as fast as possible BEFORE impact.  After impact, our muscles have the same output of energy as before but it will NOT affect the system of energy exchange between the club head and ball throughout that 400ms.  After impact, your muscles may still try to increase its energy output for a short period of time, the feeling of "accelerating through impact", but it's useless as the exchange has already occurred and the club has already significantly slowed down.

Quote:

Originally Posted by phillyk 

I think, there needs to be a mention on what our muscles do during this time period, because that is responsible for the feeling behind "accelerating through impact."  Our muscles only provide the energy necessary to move the club as fast as possible BEFORE impact.  After impact, our muscles have the same output of energy as before but it will NOT affect the system of energy exchange between the club head and ball throughout that 400ms.  After impact, your muscles may still try to increase its energy output for a short period of time, the feeling of "accelerating through impact", but it's useless as the exchange has already occurred and the club has already significantly slowed down.

I will concede one thing, you might be one of the very few people who need to think accelerate through impact. But i can tell you this, out of all my years, i have never thought that. 

If you look at the kinetic chain graph, Rory's is a bit strange, because he actually has a weird hip ability, were his hips recoil, then fire again. That's why the red line goes negative, it has nothing to do with impact at all, but is very rare in sports the involve body rotation like golf. 

The clubhead graph your seeing the clubhead speed oscilate due to impact, if there was no impact that would be a straight parabola, but hitting a 20 gram golf ball does transfer a ton of energy and does slow down the clubhead for a short time. 

Then you see that the the other body parts re-speed up. This is not do to muscle want to expend more energy, this is due to the fact that the club is pulling your body into a finish. If you look at the peaks before impact, its Hips-Core-arms-Clubhead, in order of which they peak. But if you look in the order in which they speed up again, just after impact. Its arms-core-hips. This means the clubhead and its motion is so fast it is speeding up the body into a finish. This gives the illusion of accelerating through impact, when your BODY is not accelerating on its own accord, but being influence by a body of mass moving very fast. If you were to cut of the golf shaft at just bellow the grip. there would be no re-speed up of the body, because there would be no mass moving fast that passes the body. 

Its physics, a body stays in motion until something effects it. Your body is slowing down at impact, the clubhead is speeding up to a max speed at impact. 

for Rory, his hips have lost half there speed, His core lost about a 1/4 of its speed, and his arms have lost nearly half there speed at impact. They have deaccelerated greatly. It would be physically impossible, at that moment in the swing to tell your body, "ACCELERATE". That would mean in less than a 1/10 of a second before impact your telling your hands, core, and hips to increase speed. Its not happening. The only way they would increase speed is due to an outside force, that is momentum of a massive clubhead attached to a golf shaft that is dragging your hands, which drags your arms, which turns your core, and turns your hips. Basically the energy not spent hitting the golf ball is used and sent backwards into the body, giving that slight speed up. 

cause if you were to keep accelerating, then the clubhead would have a constant increase in speed through that hole process, it doesn't its slowing down. Because energy travels from the ground up. If the clubhead is slowing down, there is no more energy acting as an accelerator for the clubhead. 

Quote:

Originally Posted by phillyk 

After impact, our muscles have the same output of energy as before but it will NOT affect the system of energy exchange between the club head and ball throughout that 400ms.

Impact is 400 microseconds. That's 0.4 ms or milliseconds. Microseconds is µs.

Quote:

Originally Posted by saevel25 

The clubhead graph your seeing the clubhead speed oscilate due to impact, if there was no impact that would be a straight parabola, but hitting a 20 gram golf ball does transfer a ton of energy and does slow down the clubhead for a short time. 

The golf ball is over 45 grams (1.62 ounces ~ 45.9 grams).

Quote:

Originally Posted by saevel25 

Then you see that the the other body parts re-speed up. This is not do to muscle want to expend more energy, this is due to the fact that the club is pulling your body into a finish. If you look at the peaks before impact, its Hips-Core-arms-Clubhead, in order of which they peak. But if you look in the order in which they speed up again, just after impact. Its arms-core-hips.

This type of thing wherein the hips "slow down" first, then the torso, the shoulders, the arms, the hands mistakenly leads many to believe that conservation of angular momentum is relevant to swinging a golf club when in fact it has almost nothing to do with it. :) (Sorry - brief divergence there - I hate the COAM conversations though, they're often the worst of people abusing a morsel of physics and trying to squish it into a golf "theory").

Quote:

Originally Posted by saevel25 

Your body is slowing down at impact, the clubhead is speeding up to a max speed at impact.

Yup.

Quote:

Originally Posted by saevel25 

The only way they would increase speed is due to an outside force, that is momentum of a massive clubhead attached to a golf shaft that is dragging your hands, which drags your arms, which turns your core, and turns your hips. Basically the energy not spent hitting the golf ball is used and sent backwards into the body, giving that slight speed up.

Plus slowing down isn't the same as stopping. Obviously in a swing your hands and thus arms are still moving. Your shoulders are still turning. There's still kinetic energy within your own body.

That said, the weight of the clubhead plays a much larger role than you'd think. Ever hit a shot and have the shaft snap just above the clubhead? You follow through really short. because you have lost a lot of the kinetic energy that could help pull you around. The clubhead weighs a lot less than your hands, but it's also moving much, much faster and the law of squaring the velocity comes into play.

Not taking a stance either way on the "accelerate through impact or not" issue, but for those of you saying that you should be getting maximum speed *at* impact and not before or after: How is that *not* a timing problem?