A body of mass `m` is rotated in a vertical circle with help of light string such that velocity of body at a point is equal to critical velocity at that point. If `T_(1), T_(2)` be the tensions in the string when the body is crossing the highest and the lowest positions then the following relation is correct

Options

A. `T_(2)-T_(1)=6 mg `
B. ` T_(2)- T_(1)=4 mg `
C. `T_(2)-T_(1)=3 mg`
D. `T_(2)-T(1)=2 mg `

Answer

A

Explanation

`f_(1)=(mv^(2))/(r)-mg=0andT_(2)=(mv^(2))/(r)+mg`
`=6 mg`
`thereforeT_(2)-T_(1)=6 mg.`