Question

A wedge of mass $2m$ and a cube of mass $m$ are shown in figure. Between cube and wedge, there is no friction. The minimum coefficient of friction between wedge and ground so that wedge does not move is

• A. $0.10$
• B. $0.20$
• C. $0.25$
• D. $0.50$

Answer 1

The correct option is B $0.20$

Formula,

$f-mg\sin \theta \cos \theta =m\left(a\right)$

$f=mg\sin \theta \cos \theta$

$\therefore f=\frac{mg}{2}$.........(1)

$mg{\cos }^2\theta +2mg=N$

$\frac{mg}{2}+2mg=N$

$N=\frac{5mg}{2}$...........(2)

$f=\mu N$

$\mu N=\frac{mg}{2}$

$\mu \frac{5mg}{2}=\frac{mg}{2}$

$\mu =\frac{1}{5}=0.2$