Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Angular kinematics

  1. Nov 16, 2006 #1
    A wheel rotates about a fixed axis. Initial angular velocity of 20 rad/s.
    During a 5 s interval the ang. velocity increases to 40 rad/s. (const angular acceleration) How many radians does the wheel turn in 5 s?

    Having a bit of trouble, not quite sure why...
    so I start out with
    w = w0 + at
    40 = 20 + a*5
    a = 4

    w^2 = w0^2 + 2*4*theta
    theta = 150 radians

    I thought that was the correct answer, however, that's not one of the choices. Anyone see what I'm doing wrong?
  2. jcsd
  3. Nov 16, 2006 #2
    I also have 150 radians... Are you sure you wrote the question word for word, or maybe there is an answer in degrees or something? It's also possible the book/test/homework/quiz/whatever it is, is wrong.
  4. Nov 16, 2006 #3
    I second the 150 radians.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook