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Potential Energy, Conservation of Energy problem 
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#1
Nov703, 07:58 PM

P: 29

Hi, I need an explanation for the following question. I also wrote down my answer. TELL me what you think and give me clues to solve this question.
There is a picture of two tracks(lines) that are horizontal and parallel to each other. In the middle of tracks, both have "bumps," Track A has concave down bump, Track B has a concave down bump. (a) Two smooth tracks of equal length have "bump"  A up, and B down. Both "bumps" have the same curvature. IF two balls start simultaneously with the same initial speed, will they complete their journey at the same time or not? If not, which will arrive first? Explain your answer clearly. > My guess is that both tracks will complete their journey at different time. But, I am not exactly sure why and how they will complete at different time. Please teach me. (b) If the initial speed of the balls is 2m/s and teh speed of the ball at teh bottom of the curve on track B is 3m/s, will the speed of the ball at the top of the curve on Track A be greater than, less than, or equal to 1m/s? Explain your answer clearly. > The speed will be exactly 1m/s because w = mgh can be applied. Because the mass, height and g(9.9m/s^2) are the same in both cases, the answer will be 1m/s. Am I right??? Or am I totally ignorant? 


#2
Nov703, 08:23 PM

P: 837

I may be misunderstanding the problem, however. I interpreted it like this: the balls are initially at zero height with speed 2 m/s. The ball on track B ends up at height h with speed 3 m/s, and the ball on track A ends up at height +h with unknown speed. If so, the problem seems to be a trick question: given the information stated, it is impossible for the ball to reach the top of track A; it doesn't have enough kinetic energy to start with. 


#3
Nov803, 08:13 AM

Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,353




#4
Nov803, 11:19 AM

Mentor
P: 41,323

Potential Energy, Conservation of Energy problem



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