A block of mass `4kg` is placed on a rough horizontal plane A time dependent force `F = kt^(2)` acts on the block where `k = 2N//s^(2)` Coefficient of friction `mu = 0.8` force of friction between the block and the plane at `t = 2s` is

Options

A. 8 N
B. 4 N
C. 2 N
D. 32 N

Answer

A

Explanation

(a) `f_("max")=mu mg=0.8xx4xx10=32N`
At t=2s. F`=kt^(2)(2)(2)^(2)=8N`
Since applied force `f ltf_("max")`, force of friction will be 8N.