Two blocks A and B of masses 3m and m respectively are connected by a massless and inextensible string. The whole system is suspended by a massless spring as shown in figure. The magnitudes of acceleration of A and B immediately after the string is cut, are respectively
A) \[\frac{g}{3},\frac{g}{3}\]
B)\[g,\frac{g}{3}\]
C) \[\frac{g}{3},g\]
D) \[g,g\]
Correct Answer:
C
Solution :
Sol. Before the string is cut \[kx=T+3mg\] ?(i) \[T=mx\] ?(ii) \[\Rightarrow \] \[kx=4mg\] After the string is cut, T = 0 \[a=\frac{kx-3mg}{3m}\] \[a=\frac{4mg-3mg}{3m}\] \[a=\frac{g}{3}\uparrow \]