# Homework Help: Glancing Collision and Kinetic Energy

1. Mar 5, 2013

### njuice8

A mass m1 = 6.20 kg is moving North with a velocity of v1 = 13.5 m/s when it collides perpendicularly with another mass m2 = 4.40 kg moving East with a velocity of v2 = 8.80 m/s. Mass m1 runs into mass m2 in an inelastic collision and both masses stick together and move off after the collision at an angle θ = 56.3˚.
What will be the velocity of these two masses after the collision?
How much kinetic energy was lost in this inelastic collision?

My work so far:
P initial:
1: x - 0 y - 6.2(13.5) = 83.7
2: x - 4.4(8.8) = 38.72 y - 0
P final:
1 & 2: x - 10.6(Vfcos56.3) = 5.9Vf y - 10.6(Vfsin56.3) = 8.8Vf

I don't know what to do next.....

Also for the kinetic energy what would I do? Thanks!

2. Mar 6, 2013

### haruspex

Momentum will be conserved in each direction, right? So equate the total x momentum before to the x momentum after, and similarly y (but either will do to determine Vf; they've given you more information than you need).
Compute the KE before and the KE after.