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

Just before the string is cut, force on the spring pulling up =kx=3mg
After string is cut , free body diagram of block A is as shown in figure (i)
`therefore 2ma_A=3mg-2mg`
or `a_A=(mg)/(2m)=g/2`
Free body diagram of block B as shown in figure (ii)
`therefore ma_B=mg or a_B=g`