MCQ
A block of mass $10 \,kg$. moving with acceleration $2 \,m / s ^2$ on horizontal rough surface is shown in figure The value of coefficient of kinetic friction is ...........
  • $0.2$
  • B
    $0.4$
  • C
    $0.5$
  • D
    $0.1$

Answer

Correct option: A.
$0.2$
a
(a)

$a=2\,m / s ^2$

$g=9.8\,m / s ^2$

$Friction force = \mu g$

$=\mu \times 10 \times 9.8$

$=98\,\mu$

Net force $=$ External force $=$ friction force

$m \times a =40-98\,\mu$

$2 \times 10 =40-98\,\mu$

$98 \mu =40-20$

$=20$

$\mu=\frac{20}{98}=\frac{10}{49}=0.20$

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