A body of mass m hangs at one end of a string of length l , the other end of which is fixed. It is given a horizontal velocity so that the string would just reach where it makes an angle of `60^(@)` with the vertical. The tension in the string at mean position is

Options

A. 2 mg
B. mg
C. 3 mg
D. `sqrt3 mg`

Answer

A

Explanation

When body is released from the position P (inclined at angle `theta` from verttical ) then velocity at mean position
`v=sqrt(2gl(1- cos theta)`
`therefore` Tension at the lowest point `=mg+(mv^(2))/(l)``=mg+(m)/(l)[2gl(1-cos 60)]`
`=mg+mg`
`2mg`