Alright I mostly understand everything now, thanks. But I still have a problem on part C, with the moment of inertia at the bottom. For the ball, i used I=2/3mr^2, which yielded 2.08, and for the hoop I used I=mr^2 and got 3.13, but I was still marked wrong. I'm not sure wether the work is wrong...
Homework Statement
A hollow, 50N ball and a 50N hoop are released from rest at the top of a 3m long ramp. Both objects have a diameter of .5m. If the ball reaches the bottom in 5s, and the hoop in 7s, find (for each object):
a. velocity at the bottom
b. angular speed at bottom
c. moment of...