A body of mass $10 \mathrm{~kg}$ is kept on a horizontal surface. The coefficient of kinetic friction between the body and the surface is 0.5 . A horizontal force of $60 \mathrm{~N}$ is applied on the body. The resulting acceleration of the body is about

• Correct answer
  A

  $1 \mathrm{~ms}^{-2}$
• B

  $5 \mathrm{~ms}^{-2}$
• C

  $6 \mathrm{~ms}^{-2}$
• D

  zero

Solution

Given, mass of the body, $m=10 \mathrm{~kg}$ Coefficient of kinetic friction, $\mu_k=0.5$ Force applied in horizontal direction, $F=60 \mathrm{~N}$
Let $f$ be the frictional force on the body. Thus, $m a=F-\mu m g$ $=60-10 \times(10)(0.9)=60-50$ $\Rightarrow 10 \times a=10 \Rightarrow a=1 \mathrm{~m} / \mathrm{s}^2$

Hence, the correct answer is option: 'A'.