Problem 8) Conservation of Momentum in Collisions III A 1200 kg car traveling in
ID: 1774596 • Letter: P
Question
Problem 8) Conservation of Momentum in Collisions III A 1200 kg car traveling initially with a speed of 25.00 m/s to the right crashes into a 9000 kg truck initially moving in the same direction with a speed of 20.00 m/s. After the collision, the velocity of the car is 18.00 m/s to the right. a) b) c) d) e) f) During the collision, is there a net force acting on the system of the car + truck? What does this tell you about the total momentum of the system? Solve for the velocity of the truck after the collision. Use your answer to b) to explain why this cannot be a perfectly inelastic collision. Find the total kinetic energy of the system (car + truck) before the collision. Find the total kinetic energy of the system (car+truck) after the collision. Use your answers to d) and e) to determine if this is an elastic collision or an inelastic collision. Problem 8 (b) 20.93 m/s2.175 x 106J (e) 2.166 x 106 JExplanation / Answer
(A) during collision, fnet = 0
so momentum of system will not change.
(B) Applying momentum conservation,
(1200 x 25) + (9000 x 20) = (1200 x 18) + (9000v)
v = 20.9 m/s
(C) for this collision to be perfectly inelastic collision,
after collision velocity of car and truck have to be equal that is not the case.
(d) Ki = (1200 x 25^2 / 2) + (9000 x 20^2 / 2)
Ki = 2175000 J
(e) Kf = (1200 x 18^2 / 2) + (9000 x 20.9^2 /2)
Kf = 2160000 J
(f) energy is not conserved hence it is not elastic collison.
Ans: inelastic