A) \[2\frac{3}{7}\,s\]
B) \[3\frac{3}{7}\,s\]
C) \[4\frac{3}{7}\,s\]
D) \[5\frac{3}{7}\,s\]
Correct Answer: B
Solution :
Let the length of each train \[=x\,m.\] Then, speed of first train \[=\frac{x}{3}m/s\] Speed of second train \[=\frac{x}{4}m/s\] They are moving in opposite Direction \[\therefore \] Relative speed \[=\frac{x}{3}+\frac{x}{4}\] \[=\frac{4x+3x}{12}=\frac{7x}{12}m/s\] Total length \[=x+x=2x\,m\] \[\therefore \] Time taken \[=\frac{2x}{\begin{matrix} 7x \\ 12 \\ \end{matrix}}=\frac{24}{7}=3\frac{3}{7}s\]You need to login to perform this action.
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