All else being the same, will a heavier golfer hit the ball a bit farther than a lighter golfer?
For convenience let’s just look at using a driver with no divots to account for.
Conventional wisdom is that all that matters is clubhead speed. (And making contact and clubhead material etc…but I am asking about all those being equal.
However in a broader sense, the club and operator form a single (almost) rigid body. When a moving object strikes a stationary object, the motion imparted to the struck object depends on the momentum of the striking object.
(Granted - the golfer isn’t in motion in the air, but hopefully has his feet planted firmly on the ground.)
Given that a heavier golfer will have more momentum to impart, could the ball end up travelling a bit faster and go farther?
I suspect the effect is negligible, likely dependent on the ratio of the masses, with the ratio being so high that its just the velocity of the striking object (clubhead speed) that counts.
I can’t answer the physics question, but in no way is the shaft of a gold club rigid. It flexes quite a bit - and in fact you can really feel it flexing when using a iron correctly. It flexes to a much less noticeable extent with a driver.
But in any case, the club is swinging around the golfer. The golfers weight isn’t behind the club, it’s the axis of rotation.
The swinger will make a small amount of forward motion, so a heavier golfer will deliver a bit more force at the same club head speed. However, if the extra mass is “muscle mass”, then the golfer will have more speed.
All that matters is club head speed (and the spin on the ball, and the aerodynamics of the ball). That is, ignoring altitude, wind speed, moister content, etc. Some of the longest hitters on tour are pretty average sized guys (Rory Mcilroy, for instance) even if they are very fit. Taller guys, theoretically, have an advantage but that’s because they have a longer lever arm. Dustin Johnson, one of the longest hitters on tour, is also one of the tallest. But being tall doesn’t automatically translate into higher club head speed.
You can’t ignore the flex of the shaft. Watch a slo-mo of John Daly’s drive sometime.
A lot of factors affect the amount of club head speed a golfer can impart. But as far as the golf ball is concerned (**), how the speed of the club head was generated is a non-issue.
(**) As opposed to the announcers, who appear to be concerned with everything including the laces on the golfer’s shoes.
The speed is not all that matters: The mass of the club head matters, too. And since the arm of the club has nonzero rigidity, the mass of everything else moving matters too, though this is going to be a very small effect.
From a physics standpoint, that’s absolutely true. I may not be very smart, but I’m smart enough not to argue physics with you <g>.
From a purely physics point of view, if you want to absolutely slaughter a golf ball, hit it with a golf club which has a club head with roughly the same mass as a locomotive at the same speed you swing your normal golf club. And that is the assumption the OP wants us to make.
Of course, if that was the only factor in play nobody would be bragging about their new titanium driver. Everyone would be bragging about their new lead / depleted uranium driver.
But as a practical matter all golf driver heads are built as light as possible - roughly 195 to 205 grams. (Yes, I know weight, mass, not the same thing. But for the moment let’s assume that we’re all at sea level on planet Earth.) And it’s the same reason why golf club shafts are so ridiculously light. (Pick up a naked golf club shaft some time - it’s like picking up a feather!) The manufacturers are attempting to develop a product that’s as light as possible while still being the right size and able to withstand the impacts they’re going to be experiencing.
Oh, and those long drive champions? They use the same components as we do - but the shafts on their drivers are absurdly long.
And lighter heads are valued because all else isn’t equal: Any given person can get more speed out of a lightweight head than out of a heavier head. But the OP told us to ignore that, and assume that we’re somehow getting the same head speed on all of them.
Long shafts are no longer authorized. The Long Drive Association LDA requires USGA conforming clubs that limit overall length to 48" except putters (putter length and anchoring changes next year). Comes from Appendix II in the USGA rules. The shafts generally have a higher kick point due to the strength of the players. Driver head lofts are lower than typical on the pro tours. Most tour pros use lofts from 8 degrees up to 10.5 deg. Long drive pros use clubheads available in lofts as low as 3 degrees.
Distance comes from club head speed, launch angle, and spin rate. Pros spend hours on launch monitors as the club manufactures change out shafts of different stiffness, shaft weights, kick points. Heads are changed with regard to loft, heel/toe weighting, forward/rear weighting, and lie angle. And they mess with grips to add more variables. You can google “optimum launch angle and spin rate” for more information.
The rigidity/stiffness of the shaft and golfer matter too. It’s more apparent in a sport like baseball. If you throw a bat 75 mph at a 90 mph fast ball, you aren’t going to hit a home run. You need the rigidity of the batter’s arms to hit the ball far. Same concept for golf, but less evident.
I don’t believe it. Rigidity matters to get the head speed up. The amount of extra force conveyed by the hands through the shaft through the club head to the ball during the fraction of a millisecond of contact is insignificant compared to the head speed squared times head mass.
All else being the same, a heavier golfer who’s clubhead speed is 120mph will drive the same golf ball, in the same wind conditions, the same distance (not counting roll), as a lighter golfer who’s clubhead speed is 120mph.
A lighter golfer who’s clubhead speed is 120mph will out-drive a heavier golfer who’s clubhead speed is only 100mph.
Upon initially reading your question, I sided with conventional wisdom. However, after reading it a few more times, I now understand that you’re asking a Conservation (of momentum) question.
Yes, theoretically, the heavier person could hit further because all other variables being equal, his “system” (dynamic components of his body + club) possesses and can impart more momentum than a lighter person’s.
In reality, like you said, the momentum effects are tiny. There are a number of other variables that have a larger practical effect, such as technique, club selection, and environmental conditions.
Momentum is mass times velocity. If the golfer isn’t moving, he has no momentum. In reality, of course, parts of his body (his arms, hips, etc.) are moving, so they contribute somewhat, but the details seem complicated. To a first approximation, I think the mass and velocity of the club is really all that matters. The final momentum of the ball can’t be more than the momentum of the club (plus golfer) before the strike.
Shaft stiffness matters when you’re trying to find the best match for a golfers swing speed. Extra stiff for the gorillas, regular for the average golfer, and “L” for slower swingers. The object is to have the club face in the best position during those microseconds when the clubface is in contact with the ball.
Well of course that test is going to impart more momentum to the ball with the weights added, because you said “Re-adjust any motors to get the club head speed back up to the initial value.” Same speed with more mass = more momentum. A human being can’t arbitrarily increase his strength on demand.
Excellent thought. I think I understand what the OP is asking. Everything else being equal, the club head mass, the stiffness of the shaft, the club head speed, will the extra momentum from the golfer’s arms and body mass help impart a little more momentum to the ball?
Clearly, it would if everything were perfectly rigid. However, it’s not, and the shaft of the club acts as a spring to take the golfer’s body out of the equation in the tiny fraction of a second of impact. It should make a non-zero difference that could be calculated, but in reality with all the noise of measurement, it would be extremely hard to measure a difference (I doubt it could be done with UncleFred’s test setup, but that’s the right way to see).
This. Check out the picture here. If you look at the deformation of a baseball during contact with the bat, it should be obvious that the muscle strength and arm momentum of the batter aren’t going to play a significant role during contact; all the batter can do is store energy/momentum in the bat prior to contact. Imagine trying to cause that kind of visible deformation without the bat, and you’ll see that the mass of your arm/body won’t do a damn thing.
Likewise with a golf ball; see impact deformation photo shown here, halfway down the page. Given the flex of the club shaft and the elasticity of the flesh in the golfer’s palms, there’s no way his body could deliver significant additional force (beyond the force due to impact by the club head itself) during the brief period of impact before the ball breaks contact with the club head; it’s all about what happens before the club head contacts the ball.