question_answer

Three identical blocks of masses \[m=2\] kg are drawn by a force \[F=10.2\] N with an acceleration of \[0.6\,\,m{{s}^{-2}}\] on a frictionless surface, then what is the tension (in N) in the string between the blocks B and C?                AIEEE  Solved  Paper-2002

A) \[9.2\]  

B)                                           \[7.8\]     

C)           4                

D)           \[9.8\]

Correct Answer: B

Solution :

   The system of masses is shown below.                           From the figure.              For block A,            \[F-{{T}_{1}}=\] ma                         ... (i)              and for block B,    \[{{T}_{1}}-{{T}_{2}}=\] ma                          ... (ii)              Eq. (i) gives              \[102-{{T}_{1}}\,=2\times 0.6\,\Rightarrow \,{{T}_{1}}=102-12=9N\]              Again from Eq. (ii), we get                                 \[9-{{T}_{2}}=2\times 0.6\]              \[\Rightarrow \]                   \[{{T}_{2}}=9-1.2=7.8\,N\]