Question

A wedge is moving rightwards on which a block of mass 10kg is placed on it. Friction coefficient between the wedge and the block is 0.8. $[takeg=10m/s^2]$. Select correct alternative(s) among the following options.

• A. If wedge is moving with constant velocity then friction acting on block is 64N.
• B. If wedge is moving with constant velocity then acceleration of block is zero.
• C. If wedge is moving with $\overrightarrow{a}=2\left(\hat{i}\right)m/s^2$ then friction acting on block is 44N.
• D. If wedge is moving with $\overrightarrow{a}=10\left(\hat{i}\right)m/s^2$ then friction is 20N.

Answer 1

Answer: (B), (C), (D)

The correct options are
B If wedge is moving with constant velocity then acceleration of block is zero.
C If wedge is moving with $\overrightarrow{a}=2\left(\hat{i}\right)m/s^2$ then friction acting on block is 44N.
D If wedge is moving with $\overrightarrow{a}=10\left(\hat{i}\right)m/s^2$ then friction is 20N.

If moving with constant velocity then a = 0

so friction available = $\mu mgcos\theta$

$=\left(0.8\right)\left(10\right)\left(10\right)\left(4/5\right)=64N.$
but $mgsin\theta =60N$
so required friction is 60N.
So net force is zero.
(C) $a=2\hat{i}$
$f=mgsin37-macos37=44N$
(D) $f=mgsin37-macos37=20N$