Question

In the diagram, the spring is connected between two blocks and it is in a compressed state.

Statement-1: Normal reaction on the lower block by ground is $2mg$.
Statement-2: In equilibrium, the net external force must be zero.

• A. Statement–1 is true, statement– 2 is true; statement–2 is a correct explanation for statement–1
• B. Statement–1 is true, statement– 2 is true; but statement–2 is not a correct explanation for statement–1
• C. Statement-1 is true, statement-2 is false
• D. Statement -1 is false, statement-2 is true

Answer 1

The correct option is A Statement–1 is true, statement– 2 is true; statement–2 is a correct explanation for statement–1

If we take the entire arrangement as a system, the entire weight is balanced by normal reaction. Since the total weight of the system is $2mg$, therefore normal reaction on lower block by the ground is $2mg$.
Since the system is in equilibrium so net external force on it has to be zero. Hence, statement-1 and 2 both are correct and statement-2 is the correct explanation of statement-1.