# Inellastic Collision Problem

1. Mar 1, 2008

### klopez

The mass of the blue puck shown below is 30.0% greater than the mass of the green one. Before colliding, the pucks approach each other with momenta of equal magnitudes and opposite directions, and the green puck has an initial speed of 11.0 m/s. Find the speeds of the pucks after the collision if half the kinetic energy of the system becomes internal energy during the collision.

So...
green puck = m

blue puck = 1.30m

But I have no idea how to use conservation of energy and kinetic energy to solve this problem. Please help.

-Kevin

2. Mar 1, 2008

### Epimetheus

First, introduce suitable variables. For example, let
$$p_b, p_g, m_b, m_g$$
be the momenta and masses of the two particles. You will need others. Your claim
"green puck = m; blue puck = 1.30m" is physically meaningless. What PROPERTY of the pucks are you assigning those values?

Can you compute the kinetic energy of the system before the collision? If not, would it help to compute another property of the system (the velocity of the other puck)? What statement in the problem allows you to find this quantity?

Can you determine the initial kinetic energy?

"Half of the kinetic energy of the system becomes internal energy ... " Now, can you find the final kinetic energy? What is the final momentum? Can you solve this system of two equations?