Question

# A car, mass m1 is moving to the right on a frictionless air track. It collides...

A car, mass m1 is moving to the right on a frictionless air track. It collides with a second car, mass m2, which is initially at rest. Which of the following statements are true? (If A and E are true, and the others are not, enter TFFFT).

A) If car 1 is much lighter than m2, and the collision is perfectly elastic, car 1 will continue heading to the right with nearly its original speed after the collision.
B) If car 1 sticks to car 2, the final total kinetic energy of the car1-car2 system is less than the initial total kinetic energy of the two cars.
C) If the collision is elastic, car 1 will never come to a stop after the collision.
D) Suppose (for this statement only) that car 2 was NOT initially at rest, but was instead heading towards car 1 with equal (but opposite) momentum before the collision. After the collision, the cars must both be at rest.
E) If car 1 sticks to car 2, the car1-car2 system must be at rest after the collision.

1. If car 1 is much lighter than car 2, and if collision is perfectly elastic, then car 1 will rebound with nearly equal speed with which it was travelling before collision.

2. This is correct. When they sticks, final KE will be lower than the initial KE

3. This is incorrect. If they have same mass, the former will come to a stop and its velocity will be transferred to the later one.

4.not exactly. Initial momentum of the system is 0, final momentum will also be 0.but 0 momentum of the system does not means particles of the system will be at rest. As you can notice they were travelling with equal and opposite momentum.

5.No. if this happens, momentum conservation will be violated.

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