Perfectly inelastic collision problem

[maxdaddy]

Homework Statement

A 2000kg car moving east at 10 m/s collides with a 3000kg car moving north. They stick together and move as a unit after the collision, at an angle of 40 degrees north of east and at a speed of 5.22 m/s. Find the speed of the 3000kg car before the collision.

Homework Equations

Pi=Pf
mivi + mivi= mfvf + mfvf

The Attempt at a Solution

I tried plugging the numbers in the above equation but it did not work. The textbook gives the answer of 5.59 m/s and I cannot figure it out. Somebody give me some help please.

 

[Doc Al]

Since momentum is a vector you can break it into components. Write a separate conservation equation for east/west and north/south components. Once you have the components of the car's initial velocity, use them to find its speed.