Question

A body of mass 2 Kg is moving on a rough horizontal surface with an acceleration of $5m{s}^{-}2$ and when the horizontal force is doubled,it gets an an acceleration of $18m{s}^{-}2$. Then the coefficient of friction between the body and horizontal surface is: $(assumeg=10m{s}^{-}2)$

• A. 0.2
• B. 0.8
• C. 0.4
• D. 1

Answer 1

The correct option is B 0.8

Initially, when the body of mass 2 Kg is moving on a rough surface with an acceleration of 5 ms^-2. Then,

$m{a}_1=F-f$

$10=F-f.............\left(1\right)$

When the horizontal force is doubled, it gets an acceleration of 18 ms^-2. Then,

$m{a}_2=2F-f$

$36=2F-f........\left(2\right)$

Solving equation (1) and (2)

$36=2F-f$

$10=F-f$

$f=16N$

$\because f=\mu R$

$\mu =\frac{f}{R}$

$\mu =\frac{f}{mg}$

$\mu =\frac{16}{20}$

$\mu =0.8$