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| Bahamut974 |
 Posted: Wed Apr 23, 2008 5:10 pm Post subject: Golf Ball and Ramp Experiment. Please answer ASAP |
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Forum Freshman
Joined: 23 Apr 2008
Posts: 3
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I really need help fast for my NYS Science Experiment Test
So here is the question...
If a ball is released form a certain height and rolls into a cup pushing it and you measure how far the cup moved and you repeat the EXACT SAME THING AGAIN WITH THE SAME RELEASE POINT... WHY ARE THE MEASUREMENTS OF THE DISTANCE THE CUP TRAVELED DIFFERENT AND NOT THE SAME IF THE GOLF BALL IS RELEASED AT THE SAME RELEASE POINT ON THE RAMP AND NO FORCE IS ADDED (LIKE PUSHING THE GOLF BALL)
I need TWO reasons why this would occur (This experiment is done in a basement so no wind interference is added)
Please the test is tomorrow, please answer this question. Im realy bewildered by this enigma  |
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| serpicojr |
| Posted: Wed Apr 23, 2008 5:34 pm Post subject: |
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Forum Professor
Joined: 17 Jul 2007
Posts: 1128
Location: JRZ
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| Think about the surface of a golf ball. Also, think about your mortality. |
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| Harold14370 |
| Posted: Wed Apr 23, 2008 6:12 pm Post subject: |
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Forum Professor
Joined: 13 Apr 2007
Posts: 1477
Location: Pennsylvania
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Just thinking off the top of my head, the golf ball will have pretty much the same kinetic energy just before it goes into the cup. Now, that energy can be dissipated in several different ways. One, the cup will be slid along the floor a ways before coming to a stop. Then the energy dissipated will be the normal force multiplied by the distance the cup moves, multiplied by the coefficient of friction. The normal force will be equal to the weight of the cup, except at such times as the ball is in contact with the bottom of the cup, at which times it will be greater, or such times as it has bounced itself off the floor. The other way for energy to dissipate is for the ball to bounce a few times, losing some energy with each bounce.
I think I'll stop right there and see if you can filll in the rest of the story. |
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| SteveF |
| Posted: Thu Apr 24, 2008 4:45 am Post subject: |
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Forum Bachelors Degree
Joined: 28 May 2007
Posts: 456
Location: NC USA
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In an ideal world repeated experiments would always yield identical results. In the real world, however, there are always random fluctuations in each test. That is why we always repeat experiments numerous times and average our results.
So you are asking us to suggest reasons why each test might yield very slight differences. I think this is what you are really talking about. I can't be certain -- your message is very incomplete. In fact, I'll pause here to give you a chance to clarify your question.
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| Harold14370 |
| Posted: Thu Apr 24, 2008 6:18 pm Post subject: |
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Forum Professor
Joined: 13 Apr 2007
Posts: 1477
Location: Pennsylvania
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Well, the test is over so here is how I would answer the question. The first thing to do is decide how you would calculate it, if it could be calculated. Then think of reasons why your calculation might not work out.
It's a collision, so you have to decide if it is an elastic or inelastic collision. If elastic, then you use conservation of energy and momentum. If inelastic, it's just conservation of momentum.
The ball bounces around inside the cup and comes to rest with the cup and ball together. That makes it look more like an inelastic collision.
If it were a classical inelastic collision like where the two objects hit and stick solid, you could say the momentum of the cup plus ball is equal to the horizontal component of the momentum the ball had right before the collision. This gives you the velocity. Then you could calculate the distance with a constant deceleration of mg times the coefficient of friction.
But the ball doesn't just land in the cup and stick. It bounces around a while before it settles down, giving you variations in the normal force. Also it can end up at a different position in the cup meaning that the cup could end up at a different position even with the cup-ball system having the same center of mass. So, that would be my two answers. |
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