Question

System shown in figure is in equilibrium and at rest. The spring and string are massless, now the string is cut. The acceleration of mass $2\,m$ and m just after the string is cut will be

• A. $g/2$ upwards, $g$ downwards
• B. $g$ upwards, $g/2$ downwards
• C. $g$ upwards, $g$ downwards
• D. $2g$ upwards, $g$ downwards

Answer 1

Answer: (A)

Initially under equilibrium of mass $m$
$T = mg$
Now, the string is cut. Therefore, $T = mg$ force is decreased on mass $m$ upwards and downwards on mass $2\,m$
$\therefore a_m=\frac{mg}{m}=g$ (downwards) and
$a_{2m}=\frac{mg}{2m}=\frac{g}{2}$ (upwards)