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 alternativeT_1 and v_1 denote the tension and speed at the lowest point. T_2 and v_2denote corresponding values at the highest point.

A stone of mass m tied to the end of a string revolves in a vertical c

1.	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 alternativeT_1 and v_1 denote the tension and speed at the lowest point. T_2 and v_2denote corresponding values at the highest point.
Answer» Solution :ALTERNATIVE (a) is correct , note mg ` + T_2 = mv_2^2 // R , T_1 - mg = mv_1^2 // R` The moral is : do not CONFUSE the actual MATERIAL forces on a body (TENSION, gravitational FORCE, etc) with the effects they produce : centripetal acceleration `v_2^2//R or v_1^2//R` in this example.