Question

Two identical blocks are connected by a light spring. The combination is suspended at rest from a string attached to the ceiling, as shown in the figure- $2.190$ below. The string breaks suddenly. Immediately after the string breaks :

• A. Acceleration of both the blocks would be $g$ downward
• B. Acceleration of centre of mass of the combined block system would be $g$ downward
• C. Acceleration of upper block would be $2 g$ downward
• D. Acceleration of lower block would be $g$ upward

Answer 1

Answer: (B), (C)

As the system is in free fall centre of mass of system will fall at $g$ and on upper block net downward force is $2\, m g$ (own weight + spring force) hence its initial acceleration is $2 \,g$.