Question

Consider a situation shown in figure initially the spring is unstretched when the system is released from rest. Assuming no friction in the pulley, find the maximum elongation of the spring.

• A. $3mg/k$
• B. $2mg/k$
• C. $4mg/k$
• D. $mg/k$

Answer 1

The correct option is B $2mg/k$

Let us assume the maximum elongation of the spring is $x$ .

The loss in the potential energy of the block $m$ will be equal to the gain in potential energy by the Spring.

$⟹mgx=\frac{1}{2}k{x}^2$

$⟹x=\frac{2mg}{k}$

B is the correct Answer.