# Conservation of Energy softball pitcher

1. Jan 3, 2008

### nickhassan38

1. The problem statement, all variables and given/known data
A softball pitcher rotates a 0.250 kg ball around a vertical circular path of radius 0.4 m before releasing it. The pitcher exerts a 33.0 N force directed parallel to the motion of the ball around the complete circular path. The speed of the ball at the top of the circle is 15.0 m/s. If the ball is released at the bottom of the circle, what is its speed upon release?

2. Relevant equations
KE = 1/2mv^2
PE = mgh

3. The attempt at a solution
1/2mv^2 = 1/2mv^2 + mgh
225.125 = .125v^2 +26.4
198.725 = .125v^2
7.43
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jan 3, 2008

### dynamicsolo

I think you may want to approach this problem from an approach using work, rather than potential energy. Consider that the ball is on a circular arc from the top of the pitch to the bottom, where it is released. The force applied by the pitcher to the ball is always aligned with its instantaneous velocity (that is, the ball is undergoing a tangential acceleration). How would you work out the change in velocity along the path?

(This problem can also be done entirely with kinematics.)

3. Jan 3, 2008

23.595?

4. Jan 3, 2008

### dynamicsolo

Would you like to show us how you found that?