Question

Two blocks of masses $m_{1}and{m}_2$ are connected with a massless undeformed spring and placed over a plank moving with an acceleration ‘a’ as shown in figure. The coefficient of friction between the blocks and platform is $\mu$. Then choose the correct statement.

• A. Spring will be stretched if a > $\mu g$.
• B. Spring will be compressed if a $\le \mu g$.
• C. Spring will neither be compressed nor be stretched only if a $\le \mu g$.
• D. Spring will be in its natural length under all conditions only if both blocks are placed simultaneously.

Answer 1

The correct option is D Spring will be in its natural length under all conditions only if both blocks are placed simultaneously.

Both the blocks will have a maximum acceleration of $\mu g$.
Hence the relative acceleration between the blocks is zero under all conditions.