The total system momentum vector before the collision is approximately

[Acestein]

Envision a minor motor-vehicle accident. Car X backs out of a parking space at 1.000m/s toward the east. Car Y, whose driver searches for a place to park, travels north at 1.000m/s. Neither driver sees the other car, and the cars collide. Suppose that each car (including its driver) has a mass of 1000kg. The total system momentum vector before the collision is approximately?

a) 1000kg x m/s toward the northeast.
b) 1414 kg x m/s toward the northeast.
c) 2000kg x m/s toward the northeast.
d) zero, because the vehicles haven't hit each other yet!

It is said to be answer b, but I'm not sure how the textbook arrived at this conclusion.
Please help!

 

[JustinLiang]

Okay so draw a vector sum. Draw at arrow going east for X and an arrow going north for Y, find each of their momentums and ... Hint: triangles

 

[Acestein]

I haven't been taught to use triangles yet. So I'm a bit confused. I know that it involves pythagoras therom and i got the answer of 1414, but I'm not sure how it fits in.