A body of mass 1 kg tied to a string of length 1 m is rotating with critical velocity in a vertical circle of radius 1 m . The difference in tension as it goes from the bottom to the top of the circle is (Take `g = 10 ms^(-2))`

Options

A. 2 mg
B. 4 mg
C. 6 mg
D. mg

Answer

A

Explanation

Tension at the lowest point , `T_(max) = (mv^(2))/v +mg`
Tension at the highest point , `T_(min) =(mv^(2))/r - mg`
Difference , `T_(max) -T_(min) =(mv^(2))/r + mg -(mv^(2))/r + mg -(mv^(2))/r + mg = 2mg`