Question

In an elastic collision in absence of external force, which of the following is/are correct?

• A. The linear momentum is conserved
• B. The PE is conserved in collision
• C. The final KE is less than the initial KE
• D. The final KE is equal to the initial KE

Answer 1

Answer: (A), (D)

The final KE is equal to the initial KE

The correct options are (a) and (d)

Step 1: Conservation of momentum

1. Linear momentum will be conserved if no external force is present, as we all know.
2. The velocity of separation = Velocity of approach in an elastic collision.

So, option (a) is correct.

Step 2: Conservation of kinetic energy

1. During an elastic collision, the system maintains its speed during the impact.
2. As a result, the kinetic energy before and after the collision will be the same.

So, option (d) is correct.

Hence, the correct options are (a) and (d)