Question

For a movie stunt, an empty truck with a mass of 2000 kg goes 10 m/s and runs into a stopped car of mass 1000 kg. The truck then keeps moving and pushes the car along with it. If there are no other forces acting on this system, which best describes the results of the collision?

A. The collision is perfectly elastic.

B. Kinetic energy stays the same.

C. The momentum after the collision is greater than the momentum before the collision.

D. The speed of the combined vehicles is less than the initial speed of the truck.

Answer 1

The answer is D on edgen.

Step-by-step explanation:

D. The speed of the combined vehicles is less than the initial speed of the truck.

Answer 2

D. This is due to conservation of momentum. The initial momentum is due only to the moving truck. Since the momentum must be conserved and P=mv, the velocity of the two vehicles must be lower since their combined mass is greater.

The conservation of momentum rules out choice C.

Choice A is false since there will be damage (smashing) of the vehicles.

B is false because the smashing of the vehicles costs energy that is taken from the initial kinetic energy of the truck.