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+pinr^2)`
C. `m(g+nr)`
D. `m{g+(pi^2n^2r)/(900)}`

Answer

D

Explanation

Tension `T_("net")=(mv^(2))/(r)=mg=mromega^(2)=mg`
`mr ((2pin)/(60))^(2)+ mg=m[(pi^(2)n^(2)r)/(900)+g]`