# Homework Help: Maximum Compression of buffers for a Train

1. Nov 11, 2008

### JamesC

1. The problem statement, all variables and given/known data
I need to work out the maximum compression of buffers for a train with 1.2kg mass, travelling at 0.45m/s and the spring constant, k, is 4.8x10^3 Nm^-1

2. Relevant equations
I tried using 1/2kx^2 but I don't know if I am doing it right

3. The attempt at a solution
I couldn't attempt the question because I don't know how the velocity is put into the equation, can anyone help?

2. Nov 11, 2008

### marlon

use conservation of energy

you'll need the v to plug it in the formula for kinetic energy

marlon

3. Nov 11, 2008

### JamesC

But that's what I don't understand about the question, I worked out the kinetic energy, but where is it placed in the equation which I attempted with?

4. Nov 11, 2008

### marlon

EK + EP = E_total

The trick is to apply the above equation onto two different situations :

EK_initial + EP_initial = EK_final + EP_final

marlon