# Rotational Motion Homework: Solid Sphere Mass m, Radius r, Speed V

• nybui

## Homework Statement

A solid sphere with mass "m" and radius "r", slides (without rotating) on a frictionless horizontal surface, with speed of V.

At time t the sphere roll on a surface with friction "u", at time t the ball is starts rotating as it glides aswell. At time t the ball only rotates.

## Homework Equations

What is the balls center mass velocity as a function of time, from time t to time t.

## The Attempt at a Solution

I have been trying to take a look at the balls inertia and torque on the ball from the friction. But the only result I got was that the ball gains speed, an that is nonsence.

Plzz... help this is a homeasignment that comes down on my final grade.

I have been trying to take a look at the balls inertia and torque on the ball from the friction. But the only result I got was that the ball gains speed, an that is nonsence.
You probably have the torque going in the wrong direction. In any case, consider the translational motion.

Hint: What forces act on the sphere? Note that the sphere is slipping. Apply Newton's 2nd law.