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Question: Answered & Verified by Expert
A block of mass $m$ is lying on a rough inclined plane having an inclination $\alpha=\tan ^{-1}\left(\frac{1}{5}\right)$. The inclined plane is moving horizontally with a constant acceleration of $a=2 \mathrm{~ms}^{-2}$ as shown in the figure. The minimum value of coefficient of friction, so that the block remains stationary with respect to the inclined plane is (Take, $g=10 \mathrm{~ms}^{-2}$ )

PhysicsLaws of MotionAP EAMCETAP EAMCET 2019 (21 Apr Shift 1)
Options:
  • A $\frac{2}{9}$
  • B $\frac{5}{12}$
  • C $\frac{1}{5}$
  • D $\frac{2}{5}$
Solution:
2144 Upvotes Verified Answer
The correct answer is: $\frac{5}{12}$
The block-plane system is shown in the figure,


So, from the above free body diagram (FBD), downward acceleration,

Divided the Eq. (iii) by $\sin \alpha$ and putting the values,
$$
\begin{aligned}
& \mu=\frac{10+2 \frac{1}{\tan \alpha}}{10 \frac{1}{\tan \alpha}-2}=\frac{10+2 \times 5}{10 \times 5-2} \\
& \mu=\frac{20}{48}=\frac{5}{12}
\end{aligned}
$$

Hence, the correct option is (b).

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