A body of mass 20 kg is kept initially at rest. A force of 80 N is applied on the body then the acceleration produced in the body is `3 m//s^(2)`, force of friction acting on the body is :

Options

A. 80 N
B. 12 N
C. 20 N
D. Zero

Answer

C

Explanation

Mass of the body, `m = 20 kg`
Applied force, `F = 80 N`
Acceleration produced, `a = 3m//s^(2)`
If foce F' is used to accelerate the body. Then
`F' = ma = 20 xx 3 = 60 N`
So, force of friction `= F - F' = 80 - 60 = 20 N`