Question

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

• A. $g,g$
• B. $g,\frac{g}{2}$
• C. $\frac{g}{2},g$
• D. $\frac{g}{2},\frac{g}{2}$

Answer 1

Answer: (C)

$\frac{g}{2},g$

Immediately after cutting , the below mass $m$ will be free falling. so the acceleration of mass $m$ is $g$. But mass $2m$ goes to upward direction.
for mass 2m , $2ma=2mg-mg=mg$
$a=\frac{g}{2}$