J & K CET Medical
J & K - CET Medical Solved Paper-2012
question_answer
Two blocks, of mass 1 kg and 2 kg respectively, are connected by a spring and kept on a frictionless table. The blocks are pulled apart, so that the spring is stretched, and released from rest. At a certain instant of time, the block of mass 1 kg, is found to be moving at a speed 2 m/s. What must be the speed of the other block at this instant?
A) 1 m/s
B) 0.5 m/s
C) 4 m/s
D) 0.25 m/s
Correct Answer:
A
Solution :
According to conservation of linear momentum \[0={{m}_{1}}{{v}_{1}}+{{m}_{2}}{{v}_{2}}\] \[0=1\times 2\times 2\times {{v}_{2}}\] \[{{v}_{2}}=-1m/s\] Negative sign shows that 2 kg is pulled in a opposite direction to that of mass 1 kg.