# Can someone help me with a physics problem with momentum?

1. Jun 26, 2008

### alyson42

1. The problem statement, all variables and given/known data
A .150kg baseball is dropped from rest. IF the magnitude of the baseball's momentum is .780 kg m/s just before it lands on the ground, from what height was it dropped?

2. Relevant equations

P=mv

3. The attempt at a solution

I found the final velocity and know that the inital position is zero and the initial velocity is zero obviously. i tried to go back to the kinematic equations to solve for final position but i do not know time and i do not know acceleration.

2. Jun 26, 2008

### dirk_mec1

Use an energy balance and choose you title with care please....

3. Jun 26, 2008

### alyson42

energy balance?

4. Jun 26, 2008

### alphysicist

Hi alyson42,

You don't know the time, but are you sure you don't know the acceleration?

5. Jun 26, 2008

### alyson42

acceleration due to gravity? just 9.81 m/s? can it be that easy?

6. Jun 26, 2008

### alphysicist

Sounds good; your acceleration units aren't quite right, but maybe that's just a typo. Depending on how you set up the problem you might need to be careful with signs, but it seems to be a straightforward problem.

7. Jun 26, 2008

### alyson42

i got the correct answer. You are a genius. Thanks for the help!