Question

Two blocks of mass $2kg$ are connected by massless ideal spring constant $k=10N/m$. The upper block is suspended from roof by a light inextensible strings $A$. The system shown in equilibrium. The string $A$ is now cut, the acceleration of upper block just after the string $A$ is cut will be $(g=10/s^2)$.

• A. $20m/s^2$
• B. $0m/s^2$
• C. $10m/s^2$
• D. $15m/s^2$

Answer 1

The correct option is A $20m/s^2$

Just after the spring $A$ is cut .

$\therefore FBD$ of upper block.

$\therefore 4g=2a$

$\Rightarrow a=20m/s^2$

$\therefore$ Option $A$ is correct.