# Help on finding kinetic energy

1. Oct 13, 2004

### dg_5021

Estimate the kinetic energy acquired by a 12g nail when it is struck by a 550g hammer moving with a speed of 4.5 m/s?

How do u find the kinetic energy? i first mutiply 550 x 4.5= 2475 /12= 206.25 am i doing it right?

2. Oct 13, 2004

### Tide

Kinetic energy is

$$\frac {1}{2} m v^2$$

For your problem, you have to determine how much kinetic energy the hammer transfers to the nail.

3. Oct 13, 2004

### dg_5021

1/2 550 x 4.5 = so then it will be 1237.5J right?

4. Oct 13, 2004

### brewnog

Work on those units chuck...

5. Oct 13, 2004

### Fredrik

Staff Emeritus
I think this is a very strange question. You can calculate the hammer's energy, but you can't know how much of it is transfered to the nail. Is somebody holding the hammer? Is somebody throwing it? Will it bounce?

What you've calculated is the hammer's energy, but if you want the answer in Joules you should use kilograms, not grams, as your unit for mass.