500
A 1,000kg car moving east with a speed of 40 m/s collides head-on with a 1,500kg truck going west at 20 m/s. The car and truck stick. What is the speed and direction of the combined mass of metal?
p = 40,000-30,000 = 10,000 east
v=p/(m1+,2)=10,000/2,500 = 4 m/s east