Two blocks A and B of masses 2m and respectively, are connected by a massless and inextensible string. The whole system is suspended by a masslessspring as shown in the figure. The magnitude of acceleration of A and B, immediately after the string is cut, are respectively

Options

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

Answer

B

Explanation

In equilibriium position, the resotring force in spring is, `F=2mg+mg=3mg.`After the string is cut, free body diagram of block `A` is shown in figure, . The acceleration `a` in the block `A` is
`2ma=3mg-2mg=mg`
or `a=(mg)/(2m)=(g)/(2)`
Free body diagram of block `B` is shown in figure. The acceleration `a^(')` in the block `B` is
`ma^(')=mg `or `a^(')g`