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Homework Help: Rotational Motion of a cylinder

  1. Feb 15, 2008 #1
    1. The problem statement, all variables and given/known data
    A hollow cylinder (hoops) is rolling on a horizontal surface at speed v = 4.3 m/s when it reaches a 15 degree incline (a) how far up the incline will it go? (b) how long will it be on the incline before it arrives back at the bottom?

    2. Relevant equations

    PE = KE + RE

    w = v/r

    I = mr^2

    3. The attempt at a solution

    A) I figured out letter A with conservation of Energy (yawn) distance = 7.3 m

    B)I am not sure exactly how to solve this problem. If it was a non rotating cube i could do it very easilly =D. I am sure the fact that it is rotating though affects it somehow. For a cube I would use the Kinetics equations (y = -.5gt^2 + vt + y0) to solve for time. Could someone help me out thanks =D
  2. jcsd
  3. Feb 16, 2008 #2
    the time taken to go up the incline=the time taken to come down.
    calculate time taken to go up sing simple kinamtic relations and then double it to get the desired result.

    use velocity final=0
    velocity[initial]=4.3 m/s
    distance=7.3 m

    now the important part is accln- i leave it to you to figure it out.
    use =s=ut+1/2at^2
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