A stone of mass m tied to the end of a string revolves in a vertical circle of radius R. The net forces at the lowest and highest points of the circle directed vertically downwards are: [Choose the correct alternative]

`T_(1)` and `V_(1)` denote the tension and speed at the lowest point `T_(2)` and `V_(2)` denote the corresponding values at the highest points.

Explanation

The net force at the lowest point is (mg -`T_1`) and the net force at the highest point is (mg + `T_2`) . Therefore, alternative (a) is correct. Since mg and `T_1` are in mutually directions at lowest point and mg and `T_2` are in same direction at the highest point.