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!

Homework Help: Am I doing this right? - rotational motion

  1. Jan 12, 2006 #1
    Hint: Consider the wheel's energy.
    Consider a wheel of radius 1.23 m, mass
    7.7 kg and moment of inertia I =1/2 MR^2
    (it's a solid disk). The wheel rolls without
    slipping in a straight line in an uphill direction 30 degrees above the horizontal. The wheel starts at angular speed 16.1 rad/s but the ro-
    tation slows down as the wheel rolls uphill,
    and eventually the wheel comes to a stop and
    rolls back downhill.
    The acceleration of gravity is 9.8 m/s^2
    How far does the wheel roll in the uphill
    direction before it stops? Answer in units of

    This is what I plan to do:

    1. Use:

    1/2 Iw^2 +1/2 mv^2 = mgh

    by substituting Rw for v and solving for h.

    2. "h" would equal the "y" component so I would then go on to use trig. to find the hypontenuse.

    Would that work?
  2. jcsd
  3. Jan 12, 2006 #2
    yes, it is correct
  4. Jan 12, 2006 #3
    Thanks for the confirmation. I don't think I'm good at canceling variables out as I got the wrong answer the first time (tried to cancel out the masses). But the second time around I just plugged in everything and it came out to a different and correct answer. :)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook