Physics - NLM Question with Solution | TestHub

The various forces acting on the block are as shown

As the truck moves in forward direction with acceleration , the box experiences a force$F$in backward direction,



$F=ma=40\times 2=$80 N

in the backward direction.

Its motion will be opposed by the force of friction

$f=\mathrm{\mu } N=\mathrm{\mu } mg=0.15\times 40\times 10=60 \mathrm{N}$

The acceleration of the box relative to the truck toward the rear end is

$\mathrm{a}=\frac{\mathrm{F}-\mathrm{f}}{\mathrm{m}}=\frac{80-60}{40}=0.5 \mathrm{m} {\mathrm{s}}^{-2}$

If$t$be the time taken by the box to fall off the truck

$s=ut+\frac{1}{2}{at}^2$

$5=0+\frac{1}{2}\times 0.5\times t^2$

$t=\sqrt{20}\mathrm{ }\mathrm{s}$

During this time distance covered by the truck

$x=0\times t+\frac{1}{2}\times 2\times {\left(\sqrt{20}\right)}^2=20\mathrm{ }\mathrm{m}$