A student whirls a stone in a horizontal circle of radius 3 m and at height 8 m above level ground. The string breaks, at lowest point and the stone flies off horizontally and strikes the ground after travelling a horizontal distance of 20 m. What is the magnitude of the centripetal acceleration of the stone while breaking off.

Options

A. 150 `ms^(-2)`
B. 140 `ms^(-2)`
C. `81.4 ms^(-2)`
D. 163 `ms^(-2)`

Answer

C

Explanation

`t=sqrt((2h)/(g))=sqrt((2xx8)/(9.8))=1.28s`
`v=(20)/(t)=15.63ms^(-1)`
`therefore" "a=(v^(2))/(R)=81.4ms^(-2)`