1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Rolling downhill

  1. Nov 11, 2007 #1
    A bicycle racer is going downhill at 11.0m/s when, to his horror, one of his 2.25kg wheels comes off when he is 75.0m above the foot of the hill. We can model the wheel as a thin-walled cylinder 85.0cm in diameter and neglect the small mass of the spokes.

    I need to get the velocity at the bottom of the hill and KEtotal at the bottom

    I know Kf=1/2Mv^2 + 1/2(I)w^2


    I know I=MR^2

    would you use Ki+Ui=Kf+Uf to get w? or is there another way?
  2. jcsd
  3. Nov 11, 2007 #2
    No, that looks correct.
  4. Nov 11, 2007 #3
    here was my attempt
    Kf=1/2mv^2+ 1/2Iw^2

    for im stuck on Kf
    Its a thin cylinder so I=MR^2 for w did i calculate it correct? v=wr so 11/.425= 25.8rad/s
    Ki +Ui=Kf + Uf
    so 136.125J +1653.75J= 1/2mv^2 + .4064*(25.8)^2 +0

    from here i solved for the v i plugged in 2.25kg into m and i got 38.8m/s as Vf
  5. Nov 11, 2007 #4
    am i messing up on calculating the ang velocity (w)?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Rolling downhill
  1. Downhill problem (Replies: 4)