# Homework Help: Need help!

1. Sep 28, 2010

### ducdat231

1. The problem statement, all variables and given/known data
A bowling ball with radius (R) and mass (m)hit the ground and traveled a distance (d) before it started to roll due to the force of friction cause by the coefficient of friction (mu) between the ball and the lane.
2. Relevant equations
I=2/5mR^2
F=ma
torque=I*alpha
F(friction)=mu*F
v=w*alpha
3. The attempt at a solution
Express the distance d in term of R, m, v and mu.

2. Sep 29, 2010

### aim1732

I suppose it is important that you know whether the ball as spinning or translating initially.

3. Sep 29, 2010

### ducdat231

initially the ball was as translating but after traveled distance (d) it change to spinning due to the friction with the lane

4. Sep 29, 2010

### aim1732

Then write the translation and rotation equations. The speed reduces and angular velocity increases to the point that they satisfy the condition for pure rolling. As soon as this is achieved friction ceases to act.