Question

A body of mass $8\text{kg}$ lies on a rough horizontal table. It is observed that a certain horizontal force gives the body an acceleration of $4{\text{ms}}^{-2}$. When this force is doubled, the acceleration of the body is $16{\text{ms}}^{-2}$. The coefficient of friction is (take $g=10m{s}^{-2}$)

• A. 0.2
• B. 0.3
• C. 0.4
• D. 0.8

Answer 1

The correct option is D 0.8


Let $\mu$ be the coefficient of friction,
Given,
$F-f_k=8\left(4\right)\dots \dots \left(1\right)$
and $2F-f_k=8\left(16\right)\dots \dots \left(2\right)$
(2) - 2(1) gives
$f_k=8(16-8)$
$\mu N=64$
$\mu =\frac{64}{80}$
$=0.8$