question_answer

Three equal weights of mass 2 kg each are hanging on a string passing over a fixed pulley as shown in the fig. What is the tension in the string connecting the weights B and C?

A)  Zero     

B)         13 N  

C)  3.3 M                   

D)  19.6 N

Correct Answer: B

Solution :

Referring figure\[,\]           \[2g-{{T}_{1}}=2a\]                  ? (i)             \[2g-{{T}_{1}}-{{T}_{1}}=2a\]             ? (ii) and       \[{{T}_{1}}-2g=2a\]                              ? (iii) Adding equations (i), (ii) and (iii), we get             \[2g=6a\] From equation (i), \[\Rightarrow \]   \[a=g/3\]             \[2g-{{T}_{1}}=\frac{2g}{3}\] \[\Rightarrow \]   \[{{T}_{1}}=\frac{4g}{3}=\mathbf{13}\,\,\mathbf{N}\]