1. Limited time only! Sign up for a free 30min personal 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!

Amount of energy lost to friction due to change in rotational inertia

  1. Apr 2, 2014 #1
    1. The problem statement, all variables and given/known data

    A 2.8-m-diameter merry-go-round with rotational inertia 140kg⋅m2 is spinning freely at 0.40rev/s . Four 25-kg children sit suddenly on the edge of the merry-go-round.

    a) Find the new angular speed.

    b) Determine the total energy lost to friction between the children and the merry-go-round.
    3. The attempt at a solution

    a) 0.17rev (verified)

    b) The old mass is 17.85714286kg, old angular speed is 2.513274123 ms-1
    The new mass is 117.85714286kg, new angular speed is 1.066237507ms-1

    To find the change in energy:

    0.5(117.85714286kg)(1.066237507ms-1)2 - 0.5(17.85714286kg)(2.513274123 ms-1)2

    The answer is 260j but I'm not getting it.
     
  2. jcsd
  3. Apr 2, 2014 #2
    Managed to solve it. I made a slip. It was 2.8m diameter instead of 2.8meter radius.:devil:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Amount of energy lost to friction due to change in rotational inertia
Loading...