Answer :
The kinetic energy at the lowest point = KE1 = 1/2 m v1² = 1/2 m 7 g r
= 7/2 * mgr
PE + KE at the highest point of the circle = m g * 2 r + 1/2 m v2²
Using energy conservation, 7/2 mgr = 2mgr + 1/2 m v2²
v2 = √(3gr) = speed at the top most point
Tension in the string at the highest point = T
centripetal force = T + mg
m v2² / r = T + mg
3mgr = T + mg => T = 2 mg
= 7/2 * mgr
PE + KE at the highest point of the circle = m g * 2 r + 1/2 m v2²
Using energy conservation, 7/2 mgr = 2mgr + 1/2 m v2²
v2 = √(3gr) = speed at the top most point
Tension in the string at the highest point = T
centripetal force = T + mg
m v2² / r = T + mg
3mgr = T + mg => T = 2 mg