Question

Two bodies of mass $1\text{kg}$ and $2\text{kg}$ are tied to an ideal string. The string passes over a smooth pulley as shown in the figure. The acceleration of the $2\text{kg}$ block is

• A. $\frac{g}{3}$ downwards
• B. $\frac{2g}{3}$ upwards
• C. $\frac{g}{2}$ downwards
• D. $\frac{g}{4}$ downwards

Answer 1

The correct option is A $\frac{g}{3}$ downwards

$a=\left(\frac{m_1-m_2}{m_1+m_2}\right)g=\frac{(2-1)}{2+1}g=\frac{g}{3}$

Hence, $2\text{kg}$ block have an acceleration of $\frac{g}{3}$ downwards.