question_answer

Three block A,B and C of equal to weights of mass 2 kg each are hanging on a string passing over a fixed pulley as shown in figure. What is the tension in the string connected between blocks B and C:                 

A)  zero                

B)  \[13\,N\]             

C)  \[3.3\,N\]                   

D)   \[19.6\,N\]

Correct Answer: B

Solution :

From the figure, Free body diagrams of A, B and C                         \[a=\frac{40-20}{6}=\frac{10}{3}\] Also,         \[20-T=2a\] \[\Rightarrow \]               \[T=\frac{40}{3}=13.33\,\cong 13N\]