A stone of mass 1 kg is tied to a string 2m long and it's rotated at constant speed of 40 `ms^(-1)` in a vertical circle. The ratio of the tension at the top and the bottom is
[Take g=10m`s^(2)`]

Options

A. `11:12`
B. `39:41`
C. `41:39`
D. `12:11`

Answer

B

Explanation

As ,`T_(top)=(mv^2)/(r)-mg " "......(i)`
and `T_(bottom)=(mv^2)/(r)+mg" "....(ii)`
`rArrT_("top")/T_("bottom")= ((v^(2))/(r)-g)/((v^(2))/(r) +g) = ((40 xx 40)/(4)-10)/((40xx 40)/(4) +10) = (39)/(41)`