Physics - NLM Question with Solution | TestHub

The maximum static friction on $5 \mathrm{kg}$ block will be $= 0.8 \times 50 = 40 \mathrm{N}$

But the pulling force by $3 \mathrm{kg}$ block is only $30 \mathrm{N}$. Hence $5 \mathrm{kg}$ block will not move.
Let $a_{1\mathrm{kg}}\mathit{ }\mathit{=}\mathit{ }2a$ (from constraint relation)
For $3 \mathrm{kg}$ block : $30 - 2T = 3a$ and for $1 \mathrm{kg}$ block : $T = 2a$
Solving the above two equations, we get
$a = (30/7) \mathrm{m} {\mathrm{s}}^{-2} = 4.3 \mathrm{m} {\mathrm{s}}^{-2}$