What is the Height at Which a Falling Ball Reaches a Velocity of 5.2 m/s?

[maddief]

Homework Statement

A ball falls from rest from an initial height of 5m above the ground. At what height above ground level will the ball be moving at 5.2 m/s?

Homework Equations

gravitational energy = mgh
kenetic energy=(1/2)mv^2

The Attempt at a Solution

I tried solving for both types of energy but I do not have mass so I am not sure how to solve. Please help!

 

[Zeus5966]

What you want to do is try using the conservation of energy theorem:
K_i + P_i = K_f + P_f
It starts from rest so K_i = 0, we want to find h_f, which is in P_f, so solve for that

In the end your equations should work out to be
m*g*h_i - (1/2) * m *v_f² = mgh_f
Use algebra to solve for h_f. You can see that all the masses cancel, so you don't need them, and the velocity you have is v_f! Let me know if it works.

 

[maddief]

Thank you! It worked!