A 1700 kg car travels at 20 m/s WEST and collides with a 2000 kg car traveling EAST.The collision is completely inelastic and they both come to rest.What is the velocity of the 2000 kg car?
A) 17 m/s EAST
B) 14 m/s EAST
C) 17 m/s WEST
D) 14 m/s WEST
E) 12 m/s EAST

Question

Quizplus · Accepted Answer

In an inelastic collision, the kinetic energy of the system is not conserved. However, the total momentum of the system is conserved.

Let's choose the positive direction to be East. The initial momentum of the system is:

p_initial = m1 * v1 + m2 * v2
         = 1700 kg * (-20 m/s) + 2000 kg * (v2)

where v2 is the velocity of the 2000 kg car.

After the collision, both cars come to rest. The final momentum of the system is:

p_final = (m1 + m2) * 0
        = 0

Since momentum is conserved, we have:

p_initial = p_final

1700 kg * (-20 m/s) + 2000 kg * (v2) = 0

Solving for v2, we get:

v2 = 17 m/s EAST

Therefore, the velocity of the 2000 kg car after the collision is 17 m/s EAST, which is choice A).

A 1700 Kg Car Travels at 20 M/s WEST and Collides