Spring Constant of ping-pong ball

[brncsfns5621]

A ping-pong ball weighs 2.5x10^-2N. The ball is placed inside a cup that sits on top of a vertical spring. If the spring is compressed .055m and released, the maximum height above the compressed position that the ball reaches is 2.84m. Neglect air resistance and determine the spring constant.

F= kx => k= F/x (k being the spring constant)

k = 2.5x10^-2 / (2.84 -.055)
= 2.5x10^-2 / 2.745
= .009

This is not the correct answer. Am I using the right formula for the Spring Constant?

 

[Hootenanny]

One should probably consider conservation of energy here.

 

[brncsfns5621]

The conservation of energy states that the total of all energies before the process is equal to the total energies after the process.

Forgive me, but I am not understanding how to apply that to this problem. :(

 

[Doc Al]

Write expressions for initial and final energy.