Physics - NLM Question with Solution | TestHub

For (A) : ${\mathrm{m}}_1$ is lifted off if $\frac{\mathrm{F}}{2}\ge {\mathrm{m}}_1\mathrm{g}\Rightarrow \mathrm{t}\ge 20\mathrm{s}$,

For (B) : ${\mathrm{m}}_2$ is lifted off is $\frac{\mathrm{F}}{2}\ge {\mathrm{m}}_2\mathrm{g}\Rightarrow \mathrm{t}\ge 40\mathrm{s}$

For (C) : At $\mathrm{t}=30\mathrm{s}$ acceleration of ${\mathrm{m}}_1=\frac{\frac{\mathrm{F}}{2}-{\mathrm{m}}_1\mathrm{g}}{{\mathrm{m}}_1}=\frac{30-20}{2}=5{\mathrm{ms}}^{-2}$

For (D) : At $\mathrm{t}=60\mathrm{s}$ acceleration of ${\mathrm{m}}_2=\frac{\frac{\mathrm{F}}{2}-{\mathrm{m}}_2\mathrm{G}}{{\mathrm{m}}_2}=\frac{60-40}{4}=5{\mathrm{ms}}^{-2}$

Drawing FBD of pulley : $\mathrm{F}=2\mathrm{t}$

Tension in the strings of pulley is F/2.