A stone of mass `m` is tied to a string and is moved in a vertical circle of radius `r` making `n` revolution per minute. The total tension in the string when the stone is its lowest point is.

Options

A. mg
B. `m(g+pi n r^(2))`
C. `m(g+pi nr)`
D. `m(g+(pi^(2)n^(2)r//900))`

Answer

D

Explanation

`T=mg+m omega^(2)r= m(g+4pi^(2) f^(2)r) (f=(n)/(60))`
`=m{g+(4pi^(2)((n)/(60))^(2) r)}= m{g+((pi^(2)n^(2)r)/(900))}`