Physics - NLM Question with Solution | TestHub

Hanging weights pull A leftward with $10\mathrm{N}$ and B rightward with $20\mathrm{N}$ ($g=10m/{\mathrm{s}}^2$). Limiting frictions: $f_1^{max}=0.4\times 2\times 10=8\mathrm{N}$, $f_2^{max}=0.5\times 3\times 10=15\mathrm{N}$.

For A + B together, net external horizontal force is $+10\hat{i}\mathrm{N}$, so equilibrium needs $f_1+f_2=-10\hat{i}$. Only option (C) satisfies this.

Check (C): $f_1=5\hat{i}$ gives $T=10-5=5\mathrm{N}$; $f_2=-15\hat{i}$ gives $T=20-15=5\mathrm{N}$ - consistent. Also $|f_1|=5<8$ (static) and $|f_2|=15$ (limiting) are allowed. Hence (C).