Wednesday, February 15, 2006

Reply to Erik's (of The Sand Trap fame) Comment to my Last Post

Erik over at The Sand Trap made a comment to my last post. Instead of just replying with another comment I decided to post my reply here. Oh and at his golf forum he also started a thread using the same comment but there he said my post was dumb. Erik, if I didn't know you better I would take that as an insult but since we're brothers in golf I prefer to believe you were just joking.

Here's my reply:

First let me say that I didn't ask that question and Chris Murphy,P.E. answered it but I do agree with his answer. Also, I think the question itself was hardly worth asking because as I alluded to in my post , 120 mph is 120mph no matter how you got there, whether you use acceleration or velocity (is that what you meant by being dumb, Erik?). That is assuming everything else is equal as the person who asked the question stated.

Now, on to your response. Let me respond to the first part (reprinted below):

[I]"Not only can people accelerate at different rates and arrive at the ball at the same speed (120 MPH), but it doesn't matter much how tall someone is in regards to acceleration."[/I]

I agree with both parts of this sentence if you assume if everything is equal. It doesn't matter at what rate you accelerate if you arrive at the ball at 120 mph it's 120 mph.

Second part of your response:

"[I]Besides, F = mv^2 is the better formula here, and that still ignores things like shaft flex, CoR, where you hit the ball on the clubface, etc. etc. etc. etc[/I]."

CoR and shaft flex shouldn't enter into this discussion because the person who asked the question says that everything else besides the person's height was equal so we have to assume these variables were the same.

Next part:

"[I]Finally, a taller person likely has longer arms, too, and since arms weigh more than a club's shaft, the taller person has to accelerate more weight to the same speed. Thus they actually likely do more work than the shorter golfer.[/I]"

I agree that a taller person has longer arms and that they weigh more but I would disagree that he has to work harder to accelerate to 120 mph. You pretty much make my point in your next paragraph:

"[I]The real advantage taller golfers have is that their swing radius is longer. If they can pivot angularly at the same rate as a shorter person, the clubhead (at the outer end of the radius) moves faster. [/I]"

A taller golfer naturally creates a longer swing arc and therefore will create a greater centrifugal force than a shorter person which means he would not have to work as hard to get the clubhead to 120 mph than a guy who has a shorter swing arc. Don't foget that everything else is equal according to the original question.

You then made an additional statement in yor forum response that you didn't make in your comment to my post:

"[I]I should have said the shorter person actually has to accelerate more quickly... since he has less distance through which to achieve the speed. Though that's only if players swing at the same tempo...[/I]"

This statement further validates my statement that the shorter guy has to work harder to accelerate his club to achieve the same impact speed as the taller golfer.

Did this make any sense or are we still standing on the opposite sides of the fence and can we all be friends?

Golf Times


Blogger Erik @ The Sand Trap said...

No, we don't agree, because there are simply too many other variables to consider. Tempo, how much wrist hinge and "lag" a swing employs, etc. The list is huge and you can't lump it in with "all other things being equal" because that's 100 other things... it's a cop-out. The original post was silly in how simple it was, and misleading at best.

Though a taller golfer needs less angular velocity to reach clubhead velocity of 120 MPH, the weight of his arms more than counters this. "All things being equal," the taller golfer has to do more "work" to reach 120 MPH. I'm using the classic definition of work: energy expended. Not whether it feels like it's harder to do or not.

Furthermore, CoR and shaft flex do matter because a swing that's still accelerating when it reaches 120 MPH versus a swing that's slightly decelerating at impact will behave differently with the same CoR and shaft flex.

Again, the initial post and even this one are far too simple. It's misleading. There are a lot more things to golf than the speed of a clubhead at impact, regardless of how tall the people that swung them are.

It was a "dumb" post because it "dumbed" the golf swing down to a level beyond silly.

2:01 PM  

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