Spring-launched clown: finding acceleration and maximum speed

[jessicak]

Homework Statement

A circus clown of mass 52.0kg is launched vertically from a springloaded cannon with spring constant 3.5x10³N/m. The clown attains a height of 4.5m above the initial position (when the spring was compressed).
a) How far was the spring compressed before launch?
b) what is the maximum acceleration of the clown during launch?
c) what is the maximum speed of the clown?

Homework Equations

mgh=1/2kx²

The Attempt at a Solution

I found the answer to part a (1.145m) using the relation above, but I am stuck on acceleration. I know I can find speed if I know acceleration. Any help would be appreciated!

 

[PhanthomJay]

Calculate speed by using energy methods...at what point is speed at its maximum? For max acceleration, at what point is the net force at a maximum? that's where a_max ocurs, found by using Newton 2.