# Potential vs Kinetic Energy Help

1. Oct 2, 2008

### pinkvoid

SO I am writing this fortran 95 program and the problem statement is the following:

-Calculate the potential energy, kinetic energy, and total energy when a ball with an
initial velocity of 0 is dropped from a 100 m building.

KE = 1/2mv^2
PE = mgh
v = (2gh)^(1/2)

The main issue I am having is the fact that the problem never gave a mass. I know
that from the law of conservation of energy that I can set KE=PE and cancel out the
masses. However this doesn't really get me anywhere. So far I have calculated all of
my velocities that I need. But now I am stuck. Unless there is some super easy way to
solve this and I just don't see it...

mgh=(1/2)mv^2

gh=(1/2)v^2 <=== This doesnt get me anywhere though

2. Oct 2, 2008

### buffordboy23

$$mgh = \frac{1}{2}mv^{2} \rightarrow v = \sqrt{2gh}$$

Take the square root of both sides. =)

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