1. The problem statement, all variables and given/known data A car moving to the right at 40 m/s has a mass of 2000 kg. It strikes a car of mass 1500 kg and both cars immediately come to rest. What was the speed and direction of the second car just prior to the collision? 2. Relevant equations pinitial=pfinal p=mv K=1/2mv2 3. The attempt at a solution In determining the speed of the second car, I set up my formula to try to resemble what the problem provides in how the first car is moving: If pinitial=pfinal, then: m1v1=m2v2 I set it up like this since we're only told that the first car is traveling in a given direction towards the second car and we we want it so that we can find v2. So: (2000 g) (40 m/s) = (1500 g)v2 v2=53.3 m/s Otherwise, I'm not sure what approach to take the find the direction. I thought maybe in the x direction with sin equaling 180 degrees with car one in applying the kinetic energy equation but I am not exactly sure if this is correct.