JEE Main & Advanced
Physics
NLM, Friction, Circular Motion
Question Bank
Self Evaluation Test - Laws of Motion
question_answer
Two blocks A and B of masses 3 m and m respectively are connected by a massless and inextensible string. The whole system is suspended by massless spring as shown in figure. The magnitudes of acceleration of A and B immediately after the string is cut, are respectively:
A)\[\frac{g}{3},g\]
B)\[~g,\text{ }g\]
C)\[\frac{g}{3},\frac{g}{3}\]
D)\[g,\frac{g}{3}\]
Correct Answer:
A
Solution :
[a] Before cutting the string \[kx=T+3\text{ mg }...\text{(i)}\] \[\text{T=mg }...\text{(ii)}\] \[\Rightarrow \text{kx=4mg}\] After cutting the string \[T=0\] \[{{a}_{A}}=\frac{4mg-3mg}{3m}\] \[{{a}_{A}}=\frac{g}{3}\uparrow \text{ and }{{a}_{B}}=\frac{mg}{m}=g\downarrow \]