Question

The string between blocks of mass m and 2m is massless and inextensible. The system is suspended by a massless spring as shown. If the string is cut find the magnitudes of accelerations of mass 2m and m (immediately after cutting)

A. g,g
B. g,g/2
C. g/2,g
D. g/2, g/2

Answer 1

Correct Answer - C
In situation 1, the tension T has to hold both the masses 2m and m therefore,
`T=3mg`
In situation 2, when the string is cut, the mass m is a freely falling body and its acceleration due to gravity is g.
For mass 2m, just after the string is cut, T remains 3mg because of the extension of string.
`:.` `3m-2mg=2mxxa` `:.` `g/2=a`