A 3900 kg truck traveling with a velocity of 9 m/s due north collides head-on with a 1600 kg car traveling with a velocity of 26 m/s due south. The two vehicles stick together after the collision.
(b) What are the size and direction of the total momentum of the two vehicles after they collide?
Already have the momentum and direction of the vehicles prior to the collision.

Question

A 3900 kg truck traveling with a velocity of 9 m/s due north collides head-on with a 1600 kg car traveling with a velocity of 26 m/s due south. The two vehicles stick together after the collision.
(b) What are the size and direction of the total momentum of the two vehicles after they collide? 
Already have the momentum and direction of the vehicles prior to the collision.

anonymous · Answer

We can make the assumption that momentum is conserved:$$p_{i}=p_{f}$$$$p_{t}+p_{c}=p_{tc}$$
You have all the values you need. You just need to consider directionality when substituting in (take one direction to be positive, the other will be negative).