Question

A block of mass $m$ is placed on the top of another block of mass $M$ as shown in the figure. The coefficient of friction between them is $\mu$ . The maximum acceleration with which the block $M$ may move so that $m$ moves along with it is :

• A. $\mu g$
• B. $\mu g\frac{M}{m}$
• C. $\mu g\frac{m}{M}$
• D. $\frac{g}{\mu }$

Answer 1

The correct option is A $\mu g$

Since, the block does not move in the $y$ direction, so $a_y=0$.

$\sum F_y=0$

The force in $x$ direction is given as,

$\sum F_x=m{a}_x$

$\mu mg=m{a}_x$

$\mu g=a_x$

The maximum acceleration is $\mu g$.