# Hammer and Nail

1. Feb 17, 2006

### Hughey85

Hi! Here's the question: I really need a starting block for this because I really don't know where to start.

The collision between a hammer and a nail can be considered to be approximately elastic. Estimate the kinetic energy acquired by a 15 g nail when it is struck by a 550 g hammer moving with a speed of 3.7 m/s.

Do I use this equation: (M1 * Vo) = (M1 * V1Final) + (M2 * V2Final)

2. Feb 17, 2006

### d_leet

What does it mean fopr a collision to be elastic? There is one more concept that you need to use.

3. Feb 17, 2006

### Hughey85

Ok. I got it. I came up with this formula that substitutes the inelastic equation because like you said, there is more than once concept. Here is what I used:

Kf = .5(m2) * (2m1 / m1 +m2)^2 * vo^2

m2 is the weight of the nail in kg
m1 is the the weight of the hammer in kg

I got K= .3933 J

Thanks for the help!

4. Feb 17, 2006

### d_leet

The problem said the collision was elastic not inelastic and you definitely can't use conservation of energy with inelastic collisions.