JEE Mains 05-Sep-2020 Shift 1 Solved Paper

A solid sphere of radius R carries a charge (Q+q) distributed uniformly over its volume. A very small point like piece of it of mass m gets detached from the bottom of the sphere and falls down vertically under gravity. This piece carries charge q. If it acquires a speed v when it has fallen through a vertical height y (see figure), then : (assume the remaining portion to be spherical).