A body B lies on a smooth horizontal table

Your Ultimate Guide to JEE & NEET Question Solutions

A body $B$ lies on a smooth horizontal table and another body $A$ is placed on $B$. The coefficient of friction between $A$ and $B$ is $\mu $. What acceleration given to $B$ will cause slipping to occur between $A$ and $B$

A

$\mu g$

B

$g/\mu $

C

$\mu /g$

D

$\sqrt {\mu g} $

A body $B$ lies on a smooth horizontal table and another body $A$ is placed on $B$. The coefficient of friction between $A$ and $B$ is $\mu $. What acceleration given to $B$ will cause slipping to occur between $A$ and $B$

There is no friction between the body $B$ and surface of the table. If the body $B$ is pulled with force $F$ then $F = ({m_A} + {m_B})\,a$ 

Due to this force upper body $A$ will feel the pseudo force in a backward direction. 

$f = {m_A} \times a$ 

But due to friction between $A$ and $B$, body will not move. The body $A$ will start moving when pseudo force is more than friction force. 

i.e. for slipping, ${m_A}a = \mu \;{m_A}g$

$\therefore a = \mu \,g$