Two particles `X` and `Y` of equal mass and with unequal positive charges, are free to move and are initially far away from each other. With `Y` at rest,` X` begins to move towards it with initial velocity `u`. After a long time, finally

Options

A. (a)X will stop, Y will move with velocity u
B. (b)X and Y will both move with velocities u/2 each
C. (c)X will stop, Y will move with velocity `lt`u
D. (d)Both will move with velocities `lt` u/2

Answer

A

Explanation

After along time separation will again be very large. Hence velocities again becomes same but interchanged (from momentum conservation and kinetic energy conservation).