# Homework Help: A heavy-duty stapling gun!

1. Nov 2, 2009

### Cluless

1. The problem statement, all variables and given/known data
A heavy-duty stapling gun uses a 0.151-kg metal rod that rams against the staple to eject it. The rod is pushed by a stiff spring called a "ram spring" (k = 35007 N/m). The mass of this spring may be ignored. Squeezing the handle of the gun first compresses the ram spring by 3.9 multiplied by 10-2m from its unstrained length and then releases it. Assuming that the ram spring is oriented vertically and is still compressed by 1.0 multiplied by 10-2m when the downward-moving ram hits the staple, find the speed of the ram at the instant of contact.

2. Relevant equations
U=(1/2)kx^2
(1/2)kx^2=(1/2)mv^2

3. The attempt at a solution
I have no idea what to do. My answer was 13.96 m/s but it was wrong.

Last edited: Nov 2, 2009
2. Nov 2, 2009

### Delphi51

I don't get 13.96. (1/2)kx^2=(1/2)mv^2 is not quite right because the spring still has some energy left (x = .01) when it hits.

3. Nov 3, 2009