Question

Two positively charged particles X and Y are initially far away from each other and at rest. X begins to move towards Y with some initial velocity. The total momentum and energy of the system are P and E.

• A. If Y is fixed, both P and E are conserved.
• B. If Y is fixed, E is conserved, but not P.
• C. If both are free to move, P is conserved but not E.
• D. If both are free, E is conserved, but not P.

Answer 1

The correct option is B If Y is fixed, E is conserved, but not P.

We know that electrostatic force is conservative. So the mechanical energy remains conserve when the external force is acting. Therefore, momentum is not conserve.
So (B) is the right option.