Previous Year NEET Question- Laws Of Motion L-3

Question: A body of mass $10 \mathrm{~kg}$ is moving with an initial speed of $20 \mathrm{~m} / \mathrm{s}$. The body stops after $5 \mathrm{~s}$ due to friction between body and the floor. The value of the coefficient of friction is:#

(Take acceleration due to gravity $\mathrm{g}=10 \mathrm{~ms}-2$ )

A) 0.3

B) 0.2

C) 0.5

D) 0.4

Answer: 0.4#

Solution:#

$\begin{aligned} & a=-\mu g \ & \because v=u+a t \ & 0=20+(-\mu \times 10) \times 5 \ & 50 \mu=20 \ & \mu=\frac{2}{5}=0.4\end{aligned}$