Physics - NLM Question with Solution | TestHub

For block A

For block B

The net force on block $\mathrm{A}=5-\mu {\mathrm{m}}_{\mathrm{A}}\mathrm{g}=5-0.2\times 1\times 10=3\mathrm{N}$ $\Rightarrow {\mathrm{a}}_{\mathrm{A}}=\frac{3}{1}=3{\mathrm{ms}}^{-2}\&{\mathrm{a}}_{\mathrm{B}}=\frac{{\mathrm{F}}_{\mathrm{B}}}{{\mathrm{m}}_{\mathrm{B}}}=\frac{\mu {\mathrm{m}}_{\mathrm{A}}\mathrm{G}}{{\mathrm{m}}_{\mathrm{B}}}=\frac{0.2\times 1\times 10}{2}=\frac{2}{2}=1{\mathrm{ms}}^{-2}$

Acceleration of block A w.r.t. block $\mathrm{B},\mathrm{a}={\mathrm{a}}_{\mathrm{A}}-{\mathrm{a}}_{\mathrm{B}}=2{\mathrm{ms}}^{-2}$

by using $\mathrm{s}=\mathrm{ut}+\frac{1}{2}{\mathrm{at}}^2$, Here initial relative velocity $\mathrm{u}=0,\mathrm{s}=4\mathrm{cm}$ & $\mathrm{a}=2{\mathrm{ms}}^{-2}$ $\Rightarrow \mathrm{t}=\sqrt{\frac{2\mathrm{s}}{\mathrm{a}}}=\sqrt{\frac{2\times 4\times 10^{-2}}{2}}=0.25\mathrm{s}$