Question

In a high speed chase, a policeman's car bumps a criminal's car directly from behind to get his attention. The policeman's car is moving at 40 m/s to the right and has a total mass of 1800 kg. The criminal's car is initially moving in the same direction at 38 m/s. His car has a total mass of 1500 kg. Assuming an elastic collision, determine their two velocities immediately after the bump.

Answer 1

u = cop car speed
v = perp car speed

Ui = 40
Vi = 38

initial momentum
= 1800 Ui + 1500 Vi
= 1800(40) + 1500 (38) = 129,000
(same after)
so
129,000 = 1800 u + 1500 v

now Ke
(1/2) 1800 (40)^2+ (1/2)(1500)(38)^2
= (1/2)(1800)(u^2) + (1/2)(1500)(v)^2
or
6(40)^2 + 5(38)^2 = 6 u^2 + 5 v^2

That is two equations with two unknowns. You can solve for u and v

Answer 2

teh cop car will destroy the other car because the other car is 300 pounds lighter

Answer 3

The problem statement says the collision is elastic Jeff. No energy was expended in demolition. The bumpers have magic springs.

Answer 4

Thanks guys!