tomturd Posted May 30, 2005 Report Share Posted May 30, 2005 Righty.. to solve a small argument going on in my living room. If you hit a golf ball, does the ball a) accelerate off the face of the club? b) not accelerate off the face of the club, just keep going at the speed you hit it? Probably pretty simple for those who remember GCSE physics :P Quote Link to comment Share on other sites More sharing options...
Siders77 Posted May 30, 2005 Report Share Posted May 30, 2005 (edited) I would have to say A) Accelerate off the face of the club Edited May 30, 2005 by Siders77 Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted May 30, 2005 Report Share Posted May 30, 2005 a) accelerate off the face of the club? ← It can't go from no speed, to some speed, without accelerating - simple! Quote Link to comment Share on other sites More sharing options...
tomturd Posted May 30, 2005 Author Report Share Posted May 30, 2005 I would have to say A) Accelerate off the face of the club ← Why so? (thats what I think too..) Quote Link to comment Share on other sites More sharing options...
Siders77 Posted May 30, 2005 Report Share Posted May 30, 2005 Dunno, it just seemed to make more sence to me. :) Quote Link to comment Share on other sites More sharing options...
Tomm Posted May 30, 2005 Report Share Posted May 30, 2005 It doesn't accelerate after the club has lost contact. That would be stupid. Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted May 30, 2005 Report Share Posted May 30, 2005 Hehe... the ball compresses though (to approx 75-80% original diameter on a drive)... and only returns to shape after it has left the club head. It sorta 'wobbles' about a bit, rebounding/recompressing enough to (theoretically) make it accelerate and decelerate in the air (for a very short period of time after the strike). Depending on what sort of time frame, the ball obviously negatively acellerates to a stop, and also acellerates towards the centre of the earth due to gravity. So... actually... both are probably right in different cases ;) Edit: Acellerates... accelerates... confused :) Quote Link to comment Share on other sites More sharing options...
Tomm Posted May 30, 2005 Report Share Posted May 30, 2005 Grumble grunble bloody sports science types mumble prove me wrong grumble :) I don't see how the expansion of the ball can make it accelerate though? Quote Link to comment Share on other sites More sharing options...
RyanRs Posted May 30, 2005 Report Share Posted May 30, 2005 (edited) it accelerates to match the speed of the club hitting it. then it gets confusing.. as, if it is hit low,after accelerating to match the speed of the club, it will constantly decrease in speed due to wind resistance and gravity etc, but if hit high enough, it will decrease in speed till it has reached its maximum height then, accelerate on decent until it reaches its maximum velocity and then remain at a constant speed.! hehe! so, for anyone thinkin that if you can kill someone through force of impact by throwing a pea of the empire estate building.... Your wrong as the maximum veloicty of a pea would be reached in a couple of seconds, as apposed to a brick wich has more weight/mass. the maximum velocity is determend by its weight, size and shape and unless prepelled by something, it will not exceed its velocity limit. correct me if im wrong, but at maximum velocity, doesnt an object's impact weight double?? if so then a pea weighing like 5g, if dropped of the empire estate building will hit the ground with the impact of 1 10g pea. ?? ah, ill shut up now! Edited May 30, 2005 by RyanRs Quote Link to comment Share on other sites More sharing options...
Tomm Posted May 30, 2005 Report Share Posted May 30, 2005 correct me if im wrong, but at maximum velocity, doesnt an object's impact weight double?? if so then a pea weighing like 5g, if dropped of the empire estate building will hit the ground with the impact of 1 10g pea. ?? ← That would completely depend on the surface area. But for a pea (sphere), maybe that estimation is about right :) Quote Link to comment Share on other sites More sharing options...
RyanRs Posted May 30, 2005 Report Share Posted May 30, 2005 (edited) That would completely depend on the surface area. But for a pea (sphere), maybe that estimation is about right :) ← Ah, cool, thanx! seems i actually know something!! hehe! shame its not that usefull though! lol Edited May 30, 2005 by RyanRs Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted May 30, 2005 Report Share Posted May 30, 2005 Impact weight? I don't think there is such thing... There is impulse, which depends on the speed and mass of the body... but impact weight... never heard of it. 'I don't see how the expansion of the ball can make it accelerate though?' Imagine you have a balloon... make an 'O' with your forefinger and thumb, and then try and pull the knot of the balloon through that 'O'. Then let go. Very similar type of thing with the golf ball - the deformed part of the ball 'catches up' and can make the whole thing change speed. Quote Link to comment Share on other sites More sharing options...
tomturd Posted May 30, 2005 Author Report Share Posted May 30, 2005 Haha.. pretty much exactly the same points are being brought up as in our living room.. Tomm, surely if the ball doesnt accelerate after its lost contact with the club, it must be going at a constant rate, and as there is nothing there pushing it to go at the same speed, it must be decellerating? So therefore it starts slowing down the second it loses contact with the club? Quote Link to comment Share on other sites More sharing options...
tank_rider Posted May 30, 2005 Report Share Posted May 30, 2005 hmm, Ad you beat me to it, tis good revision for the sports engineering exam in a week :) Quote Link to comment Share on other sites More sharing options...
Tom-ass Posted May 30, 2005 Report Share Posted May 30, 2005 its important to point out though, that the balls top speed is faster than the head of the club. this is due the the face of the driver flexing inward and outward again as the ball hits, which sorta acts like a trampoline. tom Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted May 30, 2005 Report Share Posted May 30, 2005 this is due the the face of the driver flexing inward and outward again as the ball hits, which sorta acts like a trampoline. ← And hence called the 'trampoline effect' :) Coeffecient of restitution of club faces has now been limited to 0.87 for those interested ;)" Quote Link to comment Share on other sites More sharing options...
on that? u must be joking Posted May 30, 2005 Report Share Posted May 30, 2005 Imagine you have a balloon... make an 'O' with your forefinger and thumb, and then try and pull the knot of the balloon through that 'O'. Then let go. Very similar type of thing with the golf ball - the deformed part of the ball 'catches up' and can make the whole thing change speed. ← does the front of the golf ball flatten as well, or just the bit which hits the golf club? Quote Link to comment Share on other sites More sharing options...
Tartridge Posted May 30, 2005 Report Share Posted May 30, 2005 Just the rear as far as I know... *awaits Wormy to pick a fatal flaw out of what I said* :) Quote Link to comment Share on other sites More sharing options...
JT! Posted May 31, 2005 Report Share Posted May 31, 2005 Tomm, surely if the ball doesnt accelerate after its lost contact with the club, it must be going at a constant rate, and as there is nothing there pushing it to go at the same speed, it must be decellerating? So therefore it starts slowing down the second it loses contact with the club? ← Sounds right to me. :)" its important to point out though, that the balls top speed is faster than the head of the club. this is due the the face of the driver flexing inward and outward again as the ball hits, which sorta acts like a trampoline. ← The ball cannot move faster than the head of the golf club, it would be physicly impossible. Quote Link to comment Share on other sites More sharing options...
TheChai Posted May 31, 2005 Report Share Posted May 31, 2005 (edited) well in gcse terms i would have taught the answer to be B.. B ) not accelerate off the face of the club, just keep going at the speed you hit it because by newton.. force applied to an object would get an equal and opposite reaction. so its definately not goin to accelarate off the club or go faster then the speed of the club. simplistic mind of gcse student. :) must say though.. questions like this really need to be put into more detail lol.. Edited May 31, 2005 by TheChai Quote Link to comment Share on other sites More sharing options...
Tom-ass Posted May 31, 2005 Report Share Posted May 31, 2005 Sounds right to me. :)" The ball cannot move faster than the head of the golf club, it would be physicly impossible. ← it can and does... without going into too much crazy physics, you need to watch a golf ball being hit in slow motion, the the head of the club remains pretty much at a constant speed yet after only milliseconds the ball is a good few foot away from the face... the ball does travel faster than the club head tom Quote Link to comment Share on other sites More sharing options...
on that? u must be joking Posted May 31, 2005 Report Share Posted May 31, 2005 Just the rear as far as I know... *awaits Wormy to pick a fatal flaw out of what I said* :) ← hehe nah :"> was just interested in what it did it can and does... without going into too much crazy physics, you need to watch a golf ball being hit in slow motion, the the head of the club remains pretty much at a constant speed yet after only milliseconds the ball is a good few foot away from the face... the ball does travel faster than the club head tom ← Again without going into too much crazy physics but acknowledging conservation of energy, the club head has to slow down by a significant amount as soon as it hits the ball, otherwise how would you feel that you had hit the ball. Admittedly, the ball would kind of spring away from the club head, and accelerateaway from it but only whilst club face and ball were returning to normal shape, and it would stop as soon as they lost contact. I can't get my head round the wobbling thing after it leaves the club yet but can kind of see it. Andy Quote Link to comment Share on other sites More sharing options...
tank_rider Posted May 31, 2005 Report Share Posted May 31, 2005 Wormy, additional piece of information, on impact, the club head acts like it is suspended by string. I've seen some high speed video of a golf ball being hit and indeed there are shockwaves formed throughout the ball, which last long after it has seperated with the club head, effectively causing changes in acceleration. I believe what you were trying to say was that the ball, when struck, will end up with a greater velocity than the club head previously had. Therefore you use the simple conservation of kinetic energy equation. 0.5mV^2 which shows that the velocity of the club has a larger factor on the final speed of the ball than the club head mass. Due to the fact the ball has a lower mass than the club head, its velocity after impact must be greater than that of the club head before impact, resulting in acceleration off the face of the club. Quote Link to comment Share on other sites More sharing options...
Tomm Posted May 31, 2005 Report Share Posted May 31, 2005 Tomm, surely if the ball doesnt accelerate after its lost contact with the club, it must be going at a constant rate, and as there is nothing there pushing it to go at the same speed, it must be decellerating? So therefore it starts slowing down the second it loses contact with the club? ← Yeah. Or after this wobble effect has died down. Given that the frequency of "wobble" must be >50Hz (complete guess), then for the first <1/50 of a second after it leaves the club, it might still, theoretically accelerate. But then for every oscillation after that, surely the forwards wobble would be counteracted by a backwards wobble 1/50th of a second later. At which point it deccelerates due to air resistance. As for the balloon thing - I can see where you are coming from, but 99.9% of the balloon's kinetic energy must be due to the balloon accelerating off your hand (like when you flick an elastic band), rather than wobbles in the air? Quote Link to comment Share on other sites More sharing options...
Towler Posted May 31, 2005 Report Share Posted May 31, 2005 Accelerates off the club face. Noting the compression of the ball and the flex of the club shaft. Quote Link to comment Share on other sites More sharing options...
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