Question

A block of mass m is connected with another block of mass 2m by a light spring. 2m is connected with a hanging mass 3m by an inextensible light string. At the time of release of block 3m?

• A. Tension in the string is $\frac{6}{5}mg.$
• B. Acceleration of m is zero.
• C. Acceleration of 3m is $\frac{g}{2}.$
• D. Acceleration of 2m is $\frac{3g}{5}.$

Answer 1

Answer: (A), (B), (D)

The correct options are
A

Tension in the string is $\frac{6}{5}mg.$

B

Acceleration of m is zero.

D

Acceleration of 2m is $\frac{3g}{5}.$

Just after release force in spring is zero.

$\therefore a_m=0$ and $a_{2m}=a_{3m}=\frac{3mg}{5m}=\frac{3g}{5}$

$T=\left(2m\right)\left(\frac{3g}{5}\right)$

$T=\frac{6mg}{5}$