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 2002]

A) \[9.2\]

B) \[7.8\]

C) 4

D) \[9.8\]

Correct Answer: B

Solution :

[b] 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

\[102-{{T}_{1}}=2kt-0.6\Rightarrow {{T}_{1}}=102-12=9\,N\]

Again from Eq. (ii), we get

\[9-{{T}_{2}}=2\times 0.6\]

\[\Rightarrow \]   \[{{T}_{2}}=9-1.2=7.8\,N\]