How Do You Calculate the Mass of Object 2 After a Collision?

[bencdavidson]

Homework Statement

Object 1 has a mass of 2.8 kg and is moving eastward with a velocity of 7.7 m/s. It collides with a stationary object. After the collision object 1 recoils with a velocity of -2.2 m/s What is the mass of object 2?

Homework Equations

As far as I know:

Conservation of Momentum
Po=P
m1v1=m2v2
m=mass

The Attempt at a Solution

I keep trying to solve by using m1v1=m2v2

m2 = m1v1/v2

 

[zhermes]

What does conservation of momentum mean in words?
What does the momentum equation you've written (m1 v1 = m2 v2) mean (in words)?