# Homework Help: Potential Energy and Kinetic Energy Question

1. Feb 28, 2009

### gansta344u

1. The problem statement, all variables and given/known data
A bird is flying with a speed of 17.4 m/s over
water when it accidentally drops a 2.20 kg
fish.
The acceleration of gravity is 9.81 m/s2 .
If the altitude of the bird is 7.70 m and air
resistance is disregarded, what is the speed of
the fish when it hits the water? Answer in
units of m/s.

2. Relevant equations
i tried to do potential energy equation PEg=mgh and then since it is converted to KE i re- arange the equation KE=1/2mv^2 and i tried it and it was wrong

3. The attempt at a solution[/b

2. Feb 28, 2009

### Staff: Mentor

The change in PE will tell you the change in KE. Don't forget that the fish already had KE when it was released.

3. Feb 28, 2009

### gansta344u

so i have to add the KE of bird and PE of the fish
then use the KE=1/2MV^2

4. Feb 28, 2009

### Staff: Mentor

Add the initial KE of the fish. (How fast is the fish moving when it's released?)

5. Feb 28, 2009

### gansta344u

thanks a lot,i got it rite this time