Question

With what acceleration $a$ should the bigger box shown in the figure descend so that the block of mass $M$ exerts a force $\frac{Mg}{4}$ on the floor of the box?
(Hint:- Use the concept of pseudo-force)

• A. $g/4$
• B. $g/2$
• C. $3g/4$
• D. $4g$

Answer 1

The correct option is C $3g/4$

If a person inside the box observes the block, forces acting on the block are as shown in the FBD


w.r.t. to the observer, body is at rest
$\therefore N+Ma=Mg$
As per the question $N=\frac{Mg}{4}$
$\Rightarrow \frac{Mg}{4}+Ma=Mg$
$\Rightarrow a=\frac{3g}{4}$