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Author Topic: Kinetic Energy  (Read 2062 times)

bamaster

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Kinetic Energy
« on: October 28, 2003, 07:23:03 PM »
My physics textbook tells me that
Kinetic Energy = 1/2 * Mass * Velocity(squared)
which means that throwing the ball faster will increase the hitting power more than just increasing ball weight.  More power equals better pin action equals higher strike percentage.

However, a bowler like Robert Smith also has tons of revs.  Revs, flare and gravity increase friction which slows the ball down.  

But the ball does have stored energy due to its revs... so when the ball grips the dry backends, do the revs counter the deceleration?

And if so, wouldn't a ball with low flare have more stored energy than a high flare ball?

Hmmmm....

Tony
http://www.allBowling.com
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mijakame

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Re: Kinetic Energy
« Reply #1 on: October 30, 2003, 02:16:40 PM »
"A study had been done..."

new guy - I have been looking (hard and for some time) for better strike dynamics studies than the standard 6 degree, 1-3/4" offset, flat roller off the test ramp, etc.  Can you point us in the direction of some other published or otherwise accessible research?

I have read 4+ years back BTM and did not glean much and written to various ball company research departments and ABC and did not get anything useful.  Maybe I am just looking for love in all the wrong places but I am sure not finding much.

any pointers much appreciated (and thanks for the soaker)
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bamaster

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Re: Kinetic Energy
« Reply #2 on: October 30, 2003, 02:17:57 PM »
Hmmm... but all things being equal, is it possible for one ball to have more energy (upon impact) than another ball just because of the core?

I mean, the mass of a 15lb ball is the same regardless of core, right?

So how can someone claim that their ball delivers more power?

Discuss...

Tony
http://www.allBowling.com
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Ishmael

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Re: Kinetic Energy
« Reply #3 on: October 31, 2003, 07:43:59 AM »
quote:
As the ball encounters friction, if the ball is revving faster than the the actual velocity of the ball, then the ball will start gripping the lane and drive the ball forward increasing its velocity  


You've got this backwards.  When the ball encounters friction, the revs increase and the velocity decreases until they match and the ball begins to roll.
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livespive

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Re: Kinetic Energy
« Reply #4 on: October 31, 2003, 08:15:16 AM »
quote:
quote:
As the ball encounters friction, if the ball is revving faster than the the actual velocity of the ball, then the ball will start gripping the lane and drive the ball forward increasing its velocity  


You've got this backwards.  When the ball encounters friction, the revs increase and the velocity decreases until they match and the ball begins to roll.


Are you sure about that ishmael?

the less friction you have the fewer outside forces you have acting on the angular velocity of the ball.  Once the ball hits friction the angular velocity it transfered to forward velocity (roll).  Have you ever watched a guy bowl on the lanes, and the ball actually looks like it speeds up as it hits the break point?  

IT's just like a drag racer spining his tires.  The water reduces traction(friction) and the wheels spin and smoke.  once the water have evaporated, and the tires hit the dry area, the car takes off.  The tires are not spining as fast then because there are more outside forces acting on the tires (coeficient of friction mainly)
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livespive

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Re: Kinetic Energy
« Reply #5 on: October 31, 2003, 08:48:17 AM »
quote:
OK, now I've got to know, how many of us are Physics are Engineering majors to enjoy this topic?  

I'm a junior in Aerospace Engineering and just finished Physics I - III.  Are we geeks or what?


I'm a state licensed Electrical Engineer (That's what the PE is for in my signature)
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livespive

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Re: Kinetic Energy
« Reply #6 on: October 31, 2003, 08:51:01 AM »
quote:
Hi Eric,

you must have been on-line when I was puzzling over how to present what I meant.

Are you home now?

John F.
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"Practice makes Lucky"


Yeah I was just sitting here at work, when Ishmael that things move faster with more friction, so I thought I would chime in
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Eric T. Spivey, P.E.
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A_P_K

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Re: Kinetic Energy
« Reply #7 on: October 31, 2003, 08:59:49 AM »
The ball's forward velocity should decrease when it encounters friction.  This would be why bowlers complain about not getting through dry heads.

While the ball's kinetic energy is decreasing througout the lane, the potential energy is increasing.  Once the ball actually reaches the point on the lane where it begins to roll from that friction, the ball should release it's maximum potential energy and accelerate in the direction of the "roll/revs/hook".

Like John said, that should be the greatest time to strike, while the ball is using that stored energy.

I believe that John F and Ishmael were touching the same topic, but explained it a little differently.

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In the old days people used to cut wood with axes.....................now and days...............they just have Executioners do it for them!

Pin_Krusher IS a serious threat to modern day bowling wood as we know it today.

Edited on 10/31/2003 10:09 AM
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<b>The original Pin Krusher</b>

livespive

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Re: Kinetic Energy
« Reply #8 on: October 31, 2003, 09:29:16 AM »
IF forward velocity were the only thing acting on the ball then yes.
When a bowler says he can't get through the heads the angular velocity has
already translated to forward velocity in the heads, and as the ball see more friction (as the lane get drier further down the lane) the ball with slow up.

IT is the translation of angular velocity to forward velocity that cause the ball to speed up (Accelerate) for that brief time.  If it happens in the heads the ball rolls out/looses steam/slows down.  The further down the lane you can make it happen, the more energy you will have at the pins.

Example,

Let's imagine an infinite size lane.  If you throw your ball and it is not getting through the heads, the traslation of velocity is happening just about the same time that the ball hits the lane (within 5 ft) it will start slowing down and be 3 mph slower at 45 ft down the lane.  Now throw the ball and the ball goes 40ft before it breaks.  It will speed up for about a foot or twoTranslation of velocity), but if you could go another 40 ft past the pindeck you would see that this ball slows down too.
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Eric T. Spivey, P.E.
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Ishmael

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Re: Kinetic Energy
« Reply #9 on: October 31, 2003, 10:41:07 AM »
quote:
the less friction you have the fewer outside forces you have acting on the angular velocity of the ball. Once the ball hits friction the angular velocity it transfered to forward velocity (roll). Have you ever watched a guy bowl on the lanes, and the ball actually looks like it speeds up as it hits the break point?  


Whether or not friction causes the ball to rev faster or slower is dependant on the initial ball speed and the initial rev rate.

If a ball is rolling at 18mph it is rotating at 700RPM. So, if the initial ball speed is 18mph but the rev rate is less than 700RPM the ball will rev up. If the initial rev rate is over 700RPM the rev rate will reduce. Of course this is neglecting the loss in ball speed due to friction and assuming that the track is a full roller, but you get the idea.

I think the fact that the ball appears to speed up at the breakpoint is an optical illusion because of the change of direction.  It's difficult to determine speed when an object is moving directly away from you, but once the ball reaches the breakpoint and starts to arc across the lane you gain a background against which you can reference its velocity.

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bamaster

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Re: Kinetic Energy
« Reply #10 on: October 31, 2003, 02:16:28 PM »
Are there any G-forces in the curve of a bowling ball?  I mean, doesn't an Indy car actually speed up when it goes into a turn?  Powerful "turns" are seen in skiing, speed ice skating, etc... kinda like a slingshot effect.

If a bowling ball has similar characteristics, it would seem logical that the ball actually peaks its potential energy at the very end of its curve and before it begins to roll out.

Hmmm...

Tony
http://www.allBowling.com
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