Question

Two blocks of masses M and 2M are connected to a light spring constant k. That has one end fixed as shown in the figure. The horizontal surface and pulley are frictionless. The blocks are released from rest when the spring is in its relaxed state.

• A. Maximum extension in the spring is $\frac{4Mg}{k}$
• B. Maximum kinetic energy of the system is $\frac{2M^2{g}^2}{k}$
• C. Maximum energy stored in the spring is four times that of maximum kinetic energy of the system
• D. When kinetic energy of the system is maximum, energy stored in the spring is $\frac{4M^2{g}^2}{k}$

Answer 1

Answer: (A), (B), (C)

The correct options are
A

Maximum extension in the spring is $\frac{4Mg}{k}$

B

Maximum kinetic energy of the system is $\frac{2M^2{g}^2}{k}$

C

Maximum energy stored in the spring is four times that of maximum kinetic energy of the system

Applying energy equation $\frac{1}{2}k{x}^2=2mgx\Rightarrow x=\frac{4mg}{k}$