Acceleration Question

[natep]

I am curious about acceleration and the effect it has on energy transfer at impact. If you hit the ball at 120 mph accelerating, would you transfer more energy into the ball than if you hit it at 120 mph decelerating? What about 120 mph constant? Would this result in three separate distances, all things being equal? Or would they be the same?

 

[Jon Hardesty]

No difference according to science.

 

[mjstrong]

No difference according to science.

Assuming "normalized" conditions, I suppose?

If you were hitting a 6 iron out of the rough, would the accelerating stroke maintain more clubhead speed into the ball, after it started to hit some of the grass? ie, Does a (physically) stronger player have more of an advantage out of the rough because of his strength, or simply because of his clubhead speed?

 

[Michael Finney]

Assuming "normalized" conditions, I suppose?

If you were hitting a 6 iron out of the rough, would the accelerating stroke maintain more clubhead speed into the ball, after it started to hit some of the grass? ie, Does a (physically) stronger player have more of an advantage out of the rough because of his strength, or simply because of his clubhead speed?

your example of the 6 iron from the rough would be the same as off the tee....

the stronger player may be able to deliver more speed at impact from the rough - so the parameters would not be the same.....but if 3 different players (weak, normal, strong) delivered 80mph, the ball would go the same distance

 

[mjstrong]

your example of the 6 iron from the rough would be the same as off the tee....

the stronger player may be able to deliver more speed at impact from the rough - so the parameters would not be the same.....but if 3 different players (weak, normal, strong) delivered 80mph, the ball would go the same distance

So a stronger player can better resist the deceleration that the rough might cause, and therefore maintain more speed into the ball? That's what I assumed, just wondered if anybody else had anything else on it.

 

[dominicscaife]

your example of the 6 iron from the rough would be the same as off the tee....

the stronger player may be able to deliver more speed at impact from the rough - so the parameters would not be the same.....but if 3 different players (weak, normal, strong) delivered 80mph, the ball would go the same distance

But grass and dirt (rough) certainly offer more resistance than air (tee ball) to a golf club. Therefore an accelerating object would be slowed down less by greater resistance, than a decelerating object. Real world analogy - when your foot is on the gas and you need to break quickly, it's a lot harder to stop than when your already slowing down.

So the scientist in me (not a physicist, just a B.Sc. Chemistry), suggests there would be a difference.

How significant a difference there is, is the big question, I'd love to see some properly conducted experimental data on this but I haven't seen any.

Remember it could be insignificant. Or not. Most of the scientists favoured by Brian seem to suggest it's insignificant, but I'm not sure if there talking of about the simplified tee balled case, without factoring grass/ground resistances.

Maybe a question for the conference?

p.s. When double checking my classical physics 101 equations for Kinetic energy and Force - I came across this:

the kinetic energy equation by Miles Mathis

Curious what our physicists make of this paper?

 

[savydan]

Any equation I've ever seen regarding the initial velocity of the ball, only uses the velocity of the clubhead at impact, and does not account for its acceleration.

vf = final golf ball velocity
Vi = pre-impact clubhead velocity
e = impact elasticity or COR (maximum .83 for a driver - assuming sweet spot contact)
M = Clubhead mass = 205 grams (typical for driver)
m = ball mass = 45.9 grams

vf = [MVi(1 + e)] / (M + m)

 

[adamscot89]

The accelerating stroke would better resist the decellaration caused by the rough but we are speaking in terms of clubhead velocity at impact. Whether you accelerated through the rough to hit the ball at 80mph or you decelerated through the rough to hit the ball at 80mph is irrelevant, the ball has no idea how it was hit the way it was, only that it was hit in that way.

 

[Ringer]

Homer said there was a difference in 2-E, and I think there is too. It's not just speed but increase in force. I guess it all comes down to whether or no HK was right about a stressed shaft preventing a loss of COR. I think it does, but we'll know by Monday night.

 

[greenfree]

Here is an article on the subject.


Golf Swing Tempo a Result of Applied Physics: Physics Shows Swing Tempo is Key to Long Drives Not Golf Swing Speed

 

[natep]

I also read another article that said basically the same thing as the one linked above, that's why I wanted some input from the folks around here. I havent been able to find conclusive evidence either way. Definitely very interesting.

 

[westy]

freewheeling independent object.
shaft absorbtion characterisitics,
lag.....?
heavy hit?
Would a ball suspended on a string bounce faster off a speeding locomotive or a porsche travelling at the same speed?

 

[Brian Manzella]

First 5 minutes of the symposium

 

[Michael Finney]

tutelman says....you can do stuff to the ball while it's on the face.....horizontal hinge and speed the club up...and resist the blow.....but there' one little kicker....whatever force or torque you apply for these few milliseconds - you better divide by 10,000 because the shaft is effectively a string by that point.....

 

[Frans@France]

But grass and dirt (rough) certainly offer more resistance than air (tee ball) to a golf club. Therefore an accelerating object would be slowed down less by greater resistance, than a decelerating object. Real world analogy - when your foot is on the gas and you need to break quickly, it's a lot harder to stop than when your already slowing down.

IMHO grass & dirt would create an inelastic collision, so the question would be how strong you are to resist the additional mass on the clubhead in travel. If hitting to much dirt (dig/fat shot) you will decelarate and then only when having enough swing speed to begin with you will end up with enough speed when reaching the ball. If hitting it clean those 2 gram of grass/dirt on the clubface will not change the swingspeed to much in regards to the already minimum of 230 gram of clubhead mass.

 

[birly-shirly]

Would a ball suspended on a string bounce faster off a speeding locomotive or a porsche travelling at the same speed?

I think the more correct question to ask would be whether the ball would bounce faster off of either of 2 identical porsches travelling at the same speed. The difference being that one is travelling under its own steam, and the other is suspended from a locomotive by a relatively flimsy, let's say DG X100 (tipped if you like), metal tube.

 

[Bigwill]

I also read another article that said basically the same thing as the one linked above, that's why I wanted some input from the folks around here. I havent been able to find conclusive evidence either way. Definitely very interesting.

This doesn't work for me (slow backswing, start of downswing) as it relates to creating more speed. The faster my backswing and transition, the more clubhead speed I create. It would be nice if things were as simple and neat as they're presented in the paper in regards to the golf swing.

 

[natep]

This doesn't work for me (slow backswing, start of downswing) as it relates to creating more speed. The faster my backswing and transition, the more clubhead speed I create. It would be nice if things were as simple and neat as they're presented in the paper in regards to the golf swing.

Yeah I know what you mean. When I make what I feel is the most efficient swing, where it feels like all the energy is transferred to the ball, I'm swinging slower than I know I can. I get about 80% of my maximum distance doing this.

 

[welshdentist]

If it's from the rough the question has to be how much the rough stops the clubface slowing down before the ball.....affecting speed hitting the ball

To me, accel or decel or the same at impact makes very little difference. But who hits from the rough and doesn't hit grass first and therefore makes you slow down unless you hit ball first?

Flippy wristed college kid vs tour veteran. I know who i'd want hitting the rough before the ball.....


At impact, speed is speed