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

Options

A. `g//2` upwards, g downwards
B. g upwards, `g//2` downwards
C. g upwards, 2g downwards
D. 2g upwards, g downwards

Answer

A

Explanation

Net force on m
`F=mg`
so, `a=g`
Net force on 2m
`2mg-mg=2ma_(2)`
`a_(2)=g/2`