2D - Momentum Question, Grade 12 Canadian Physics

[ccvispartan]

Homework Statement

2 cars collide at an intersection.
one car which has a mass of 1,400kg has a velocity of 45 km/h;
the other car has a mass of 1,300kg and has a velocity of 39 km/h[E]
The cars has an inelastic collision. What are their velocity after the collision

Homework Equations

Conservation of momentum: P total = P total prime

The Attempt at a Solution

I have tried on numerous occasions but have not achieved the correct answer.

The correct answer should be: "30 km/h [ 51 South of East.]

I got the correct magnitude of the velocity which is 30 km/h. Easy enough, but i didn't get the degrees required. Additional vector diagram is appreciated.

 

[grzz]

Try to draw the vector diagram for the initial total momentum of the system.

 

[ccvispartan]

@grzz I figured out what i did wrong. When i calculated for the theta of the vector triangle. I simply used the velocities. Instead i tried it with m(v) and it worked for me. Thanks.

 

[grzz]

You just confirmed that it is the total momentum that is conserved and not the total velocity!