A solid uniform disc of mass `m` rols without slipping down a fixed inclined plank with an acceleration a. The frictional force on the disc due to surface of the plane is

Options

A. `(1)/(4)ma`
B. `(3)/(2)ma`
C. `ma`
D. `(1)/(2)ma`

Answer

D

Explanation

`a=(gsintheta)/(1+I//mR^(2))=(gsintheta)/(1+(1//2))`
`=(2gsintheta)/(3)`
`thereforegsintheta=(3)/(2)a`
Now, `f=(mgsintheta)/(1+mR^(2)//I)=(m(3//2a))/(1+2)`
`=(1)/(2)ma`