Physics collision momentum

[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!

 

My text book has been teaching me with formulas of momentum. However, when i attempted it by finding the momenutm of each object and then adding them together i got 2000kg x m/s toward the northeast. What am i doing wrong? some people have told me to use the triangle method, but i haven't been taught that way yet. Does this question involve p=mv?

[swansont]

You have to add the values as vectors. You're doing physics — you must have learned the pythagorean theorem by now.

[acestein]

You have to add the values as vectors. You're doing physics — you must have learned the pythagorean theorem by now.

 

I know what the pythagorean theorem is, however, i have added the vectors together before and have received the wrong answer. Now i understand why. I wasn't using the pythagorean theorem. I know how to use it, I just wasn't taught to solve this problem with the pythagorean method before.

[swansont]

I know what the pythagorean theorem is, however, i have added the vectors together before and have received the wrong answer. Now i understand why. I wasn't using the pythagorean theorem. I know how to use it, I just wasn't taught to solve this problem with the pythagorean method before.

 

Good. It's all about making right triangles, and the resultant is they hypotenuse. So if the two sides have length of 1.000, the resultant has a length of 1.414 (sqrt of 2)