Question

A box is moving upward with retardation 'a' < g, find the direction and magnitude of" pseudo force" acting on block of mass 'm' placed inside the box. Also calculate normal force exerted bysurface on block

Answer 1

Pseudo force is always directed opposite to the direction of the acceleration of the frame.

Pseudo Force = $ma$ , Where $m$ is mass of body and $a$ is acceleration of the frame.

Here box is moving upward with retardation , it means acceleration is acting downwards so pseudo force is acting upward.

$\therefore$ Pseudo Force= $ma$, $\uparrow$

Using Pseudo Force Method,

From FBD of the block,

$N+ma=mg$, ( $N$= Normal force)

$\Rightarrow N=m(g-a)$