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course phy 231
Ball on V rampsUses ball, two ramps, dominoes, TIMER
See also Pictures_of_ball_and_ramps, which includes pictures and brief descriptions of basic setups.
Make the two ramps into a wide V, with each end supported by a single domino lying on its flat side. If the ball is released from the top of one ramp, it will roll down the the bottom of the V, then up the other ramp. If it doesn't roll off the end of that ramp, it will then return to the bottom of the V and roll back up the first ramp, but not as far as its original starting point. The ball will continue rolling back and forth until it comes to rest.
Release the ball from the top of the shorter ramp. Observe how far it travels from release to the bottom of the V, from the bottom of the V to its highest point on the other ramp, and how far it travels back up the first ramp before coming to beginning to roll back down.
Report your observations:
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bottom of V to highest point on other ramp: 5.75 inches
Back up to highest point on small ramp: 3.1 inches
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Repeat, this time releasing the ball from the top of the longer ramp.
Report your observations:
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To highest point on small ramp: 5.75 inches
Going back up to the highest on longest ramp: 5.25
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Using the TIMER, release the ball and observe the clock time of release, and the clock times when the ball reaches the bottom of the V, and the clock times when reaching the highest point of each ramp. Also observe the clock time at which the ball finally comes to rest.
Report the distances you observed in the first sets of trials.
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To highest point on long ramp, 5.3 inches; back up to short ramp, 3.1 on short ramp.
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Copy the TIMER output.
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0 at release, highest point on long ramp is 1.95 seconds. Highest point on short ramp time is 3.99 seconds. Time until rest is 13.3 seconds.
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Of each set of trials where you measured the distances, express each distance as a percent of the initial distance down the first ramp.
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First distance is 88 percent of initial “drop”; next distance is 51.7 percent of initial drop.
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According to your TIMER output does it take longer for the ball to go up the longer ramp, or down?
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I got the same time for each
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You didn't include the distance from initial release to the bottom of the V. If necessary, you can quickly run the experiment again and modify your data as appropriate.
Analysis:
Assuming ball mass 60 grams and domino thickness .9 cm, how much gravitational PE did the ball lose between release and its first 'turnaround', and how much between that and its second 'turnaround'?
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Assuming that the energy lost to rolling friction between two 'turnaround' points is proportional to the distance the ball rolls between those points, how much energy do you conclude was lost in the two 'bumps' at the bottom of the V?
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Assuming the acceleration to be the same whenever the ball is on a ramp, what is the magnitude of its acceleration when on a ramp? Note that the effect of t the 'bump' must be taken into consideration.
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