# Physics momentum car question

1. Aug 12, 2015

### Hannahj1

1. The problem statement, all variables and given/known data
A collision in Phystown is being analyzed by the O.P.P. accident analysis team. A 1000 kg Toyota known to be moving at 65 km/h [W] collided at an intersection with a 3000 kg SUV moving [N]. After the collision, the two vehicles "stuck" together and the police estimate that immediately after impact the Toyota-SUV wreckage moved at 45 km/h. Based on this information, what was the speed of the SUV before the collision?

2. Relevant equations
mv1 + mv2 = v (m1 +m2)

3. The attempt at a solution
I just plugged in values into the equation that i was given from the question...
(1000)(-18.1) + 3000v2 = 12.5 (4000) -> i made E and N positive

I was just wondering if i did this right! should i do components since i have directions in y and x directions? Thank you!

2. Aug 12, 2015

### haruspex

You certainly should consider the components. You cannot add momenta that are in different directions.
Apply conservation of momentum in each of the two directions separately.