# Homework Help: Sphere on Incline

1. Oct 15, 2007

### conniechiwa

A solid sphere of uniform density starts from rest and rolls without slipping a distance of d = 3.9 m down a q = 35° incline. The sphere has a mass M = 4.6 kg and a radius R = 0.28 m.
https://online-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?courses/phys101/fall07/homework/08/03/3.gif [Broken]

Suppose now that there is no frictional force between the sphere and the incline. Now, what is the translational kinetic energy of the sphere at the bottom of the incline?

Last edited by a moderator: May 3, 2017
2. Oct 15, 2007

### conniechiwa

I figured out that the velocity is 5.6 m/s, but I don't know what the KE tran would be at the bottom without friction.

Last edited: Oct 15, 2007
3. Oct 15, 2007

### Staff: Mentor

The problem statement is incomplete, but I infer that you are being asked for the translational KE at the bottom for the two cases: the ball rolls down the incline, or it just slips down the incline (frictionless case).

If it just slips, then the KE final equals the PE initial, right? Why?

If it rolls, then some energy goes into the rolling motion (look up moment of inertia). What is the equation for the rotational energy of a sphere? What does that do to the final KE of the sphere at the bottom?

4. Oct 15, 2007

### conniechiwa

nvm i figured it out.

5. Oct 15, 2007

Doh!