# Homework Help: Help Momentum

1. Nov 12, 2007

### Sucks@Physics

Help!!! Momentum

A ball, of mass 100g, is dropped from a height of 16m. Its momentum when it strikes the ground is?

How do you do this calculation?

Thanks!

2. Nov 12, 2007

### catkin

What have you tried? Do you know what momentum is?

Last edited: Nov 12, 2007
3. Nov 12, 2007

### Dick

First you compute the velocity. Then you remember the definition of momentum. Get started with the first part.

4. Nov 12, 2007

### Sucks@Physics

Dont' I have to have time to calculate velocity? i know p=mv i just dont know the velocity

5. Nov 12, 2007

### Vidatu

Look in the formulas sticky, at the top of this page. There''s one in there which you can use to solve this.

6. Nov 12, 2007

### Sucks@Physics

i do not see the formula??

7. Nov 12, 2007

### Vidatu

$$v^2 = v_0^2 + 2 a \Delta x$$

$$\Delta x$$ is the displacement.

8. Nov 12, 2007

### Sucks@Physics

i end up getting 313.6 m/s that can't be right? a= gravity correct?

9. Nov 12, 2007

### Vidatu

You're putting in some formula wrong. Show whet you are doing, and we'll tell you where you messed up.

10. Nov 12, 2007

### Sucks@Physics

0+(2x9.8x16) = 313.6

11. Nov 12, 2007

### Vidatu

Check the formula again.

12. Nov 12, 2007

### Sucks@Physics

grrr im stupid

13. Nov 12, 2007

### patrickking

Yah A= -9.80 (Or 9.80 down) Thats the gravational force pulling down.