Question

Block A of mass 2m, B and C each of mass m are in equilibrium and at rest shown in the figure. The spring balance, pulley and strings are mass less. Now, a force mg is applied on block C in downward direction. Find the new reading of spring balance. Assume all pulleys to the frictionless.

• A. $\frac{5m}{2}$
• B. $\frac{3m}{2}$
• C. $2m$
• D. $m$

Answer 1

The correct option is B $\frac{3m}{2}$

2T - 2mg = 2ma
$\Rightarrow T-mg=ma$
2T - 2mg - 2ma
$\Rightarrow T-mg=ma$

$\Rightarrow A=\frac{2mg-mg}{2m}=\frac{g}{2}$