OT Stuff from "Getting a little extra distance..."

I feel like im in science class LOL

I'll give the science lesson a shot. My undergraduate degree is in physics, and that was only 3 years ago, so I should be able to remember most of this stuff

When the clubhead strikes the ball, the ball is accelerated at a rate directly proportional to the force applied by the club (this is where F=ma comes from). From the physics standpoint, a more useful quantity for calculating ballspeed would be the "impulse" applied to a ball. The impulse applied to a ball is basically dependent on the amount of force applied to the ball (dependent on how fast you clean the club), and the amount of time that the force is applied (how long the club and ball are in contact with each other). Whatever this impulse turns out to be happens to equal the change in momentum of the ball. Momentum turns out to equal mass*velocity (p=m*v), so if you calculate the impulse on a ball, you can find the velocity of said ball.

So, I think Slicer and Dean both have valid arguments. F=ma is useful for calculating initial acceleration of the ball, and measuring the impulse is useful for measuring the initial velocity. But, the two are closely related. Back to the golf, though A 103 SS with a 163 ball speed seems a little high. That's a smash factor of 1.58 which is higher than most touring pros (higher than any I've ever heard of). If you could post a video of your swing, that'd probably be the best way to help you out. Or even better yet, set up a lesson with your local (qualified) golf pro and take a lesson.

That seems to make sense, but how did you get to 125 without acceleration?

You're right that we need more than F=ma to get accurate ball speed, but when we are referring to clubhead speed, which produces ball speed, F=ma is a good place to start. With Trackman, we can optimize the club based on current launch, speed, and spin conditions to give us the ideal driver for our swing. I think you're going to see a bigger discussion on weighting in the future.. all based off F=ma. Its about trying to find the right mix for you: club weight, swing speed given different club weights... THEN launch and spin rates.

Thanx for articulating that picrig. The intent in my original post was to illustrate the importance of having a good rhythm, aka tempo. Swingspeed or weight shifting alone won't do it, you need both. The closer these two are to each other at the time of impact the better the result. For me thats the art of the game.

Iacas,

You seem to know your golf science. Great info.


I agree with you that F=ma is not the sole determinant, but I think that it will now be taken into consideration once the correct shaft frequency, loft, spin rate, weight, golf ball, personal trainer, mental coach etc... have been exhausted. There is a perfect mix between the weight of the head and the ball speed and I know players are already testing heavier clubs and adjusting equipment to get optimal readings from trackman.

The clubhead must accelerate to maintain shaft pressure. If A=0, we have decreased shaft pressure, and if its a negative (decelerating) it will produce bad launch angles but not make the ball go in the opposite direction. My theories are based on ideal launch conditions where a decelerating clubhead wont give consistent readings.
If the clubhead is not accelerating, it is decelerating or has reached a constant speed, which are 2 things that would kill shaft pressure and the shaft would kick. If A=0 at impact, the clubhead speed could potentially increase. I agree that the the exact acceleration at impact is not required however acceleration shows shaft pressure which is something that is not raw data on a machine...yet.

The VW/semi example is extreme. Would you rather get hit with a brick or a feather. In this case, I would rather take a feather at 60 than a brick at 10. Its not that simple because whether the light one is moving faster than the heavy one, they both moving fast and both within reasonable speeds, creating almost the same amount of force and energy. When I refer to a light club moving fast, I mean 11oz at 125mph and a heavy one weighing 13.5 oz and swinging at 115mph. Its not like the 60 mph difference with the cars.


Have you had experience with Trackman or any other launch device?

I have no disagreements with your arguements except in the narrow view. Its not in my best interest to try and swing faster. Doing that does not give me greater distance. In fact I loose distance because I'm not getting my weight behind the ball. The mass multiplier is greater than VV in this case.

"Of course?" I didn't know if you were a golfpro or someone who moderated a forum.

If you're telling me that clubhead speed is the only thing that matters and that force has nothing to do with it, I'll rest my case. If you can understand that its the force that the clubhead is providing into the back of the golf ball, I would like to hear your views. The more I think about it, the more its really the same thing. The speed of the club head is directly related to the force it can apply to another object.

If the smash factor is ball speed divided by clubhead speed, then how can we get a better smash factor with less clubhead speed? Its a ratio, so the answer is to increase ball speed and this is done through better club and shaft dynamics - which is why I brought it up. If ball speed is increased, perhaps due to a different golf ball, the we should see the smash factor go up with the same clubhead speed, right?

"'It was stated earlier that F=ma mattered - it doesn't. Clubhead speed matters"

crikey sore head


Scanned this so dont shoot me


F=MA

Totally irrelevant, what is relevant is the F at impact, then the number of variables as far as ultimate distance are concerned are pretty big.


I dont see the point of this thread!


Ironic that i posted on it.

All this F=ma stuff is missing a huge point. Force maxes out much earlier in the swing than during or just before impact. Think a moment -- acceleration is what makes a club to go to a higher clubhead speed, so I am guessing that the maximum force could even be at the moment in the transition from backswing to forward swing. As a club head approached the ball, the shaft been through a loading stage and is starting to flex forward and down because Force is not increasing at the same rate any longer, it is actually decreasing. Icarus is correct in his general concepts.

The problem in golf is to not slow just prior to impact. It is great if you can be generating some level of force later in the swing, but it will not be much at all. Your job as a golfer is not to lose speed -- there is no way the club accelerates as much in the last foot or so of arc like it does earlier in the swing. If it did, the shaft would deflect back and the club face would be very open. This is a very misunderstood part of the swing. You will not find photographic evidence of huge gains in speed in the last few inches of clubhead motion before impact -- so there is very little force showing up at this point in time.

However, it is important to have weight transfer, body mass, and firm, turning positions through impact because if you did not, the inelastic colllision of the golf ball with the club head would lose a great deal more energy into a loose, non-resisting connection to your body. The momentum transfer and the energy loss would show up in more places throughout your body and club. Think of it as the difference between dropping a ball on a concrete surface versus a gel surface (a poor analogy at best.) You want the least amount of energy loss and momentum loss going into your body as possible. If at the last instant of time before impact, your body, hands, etc., were turned into jello, the club would not cause the ball to depart with the same speed. Conservation of momentum would show up all over the place in the wiggling jello and a much less firm lever arm attachment. The wild card in all this business of trying to use words to describe the physics is the shaft. The shaft is responding and distorting all over the place, and its response time to forces that deform it depend on its own particular design properties.

So I cannot with confidence say much at all about extremely precise models of hitting a golf ball. It is a huge order of magnitude more difficult problem than calculating the quantum mechanical ground state of the hydrogen atom, even with QED corrections for several decimal places out in the answer (and omitting entirely the gravitational field.)

This thread has gotten a little contentious. I wasn't attempting to "side" w/Dean or Slicer earlier, just try to kind of expound upon what I thought they were saying.

I think that Iacas has the most valid argument. What do we hear clubmakers talk about often? Their newest club "transfer energy more efficiently to the ball." The sole goal of the swing is to maximize the energy of the ball as it leaves the clubhead. Iacas, I definitely agree with you that this isn't a simple problem and is a very high-dimension problem. To actually solve the equations involved w/all variables involved would most likely require some tensor calculus. Alas, physicists do tend to oversimplify problems (it's what we do). But, I think you're right that the kinetic energy of the clubhead (K=0.5mv^2) is most relevant if you want to know the affect of the club on the ball. Energy is conserved in the ball/club/body system. The body dissipates some of the energy in the clubhead, and energy is also lost to other places (the sound of the clubhead striking the ball, heat, ball deformation, etc), but I think you've hit the nail on the head.

Anyway, unless we're going to write out equations and actually prove something throwing words and ideas around probably won't persuade anyone who either doesn't have a background of some sort in physics or who has already decided what they believe is the most important equation to the golf swing (which seems like a somewhat ridiculous statement anyway).