Two trains C and D start running together from the same point at speeds of 70 kmph and 92 kmph respectively. If the length of the two trains together is 550 m, how long will it take for train D to cross train C?
1 min 30 sec
Since both trains are moving in the same direction, their relative speed is:
\[ \text{Relative speed}=92-70=22\text{ km/h} \]
Convert the relative speed into m/s:
\[ 22\times\frac{5}{18}=\frac{55}{9}\text{ m/s} \]
To completely cross each other, train D has to cover the sum of their lengths:
\[ \text{Distance}=550\text{ m} \]
Therefore, the time taken is:
\[ t=\frac{\text{Distance}}{\text{Relative speed}} =\frac{550}{55/9} =90\text{ seconds} \]
Convert 90 seconds into minutes:
\[ 90\text{ seconds}=1\text{ minute }30\text{ seconds} \]
hence, 1 min 30 sec
Similar Questions
A train travels \(\frac{1}{3}\) of the total distance at \(40\ \text{km/h}\), \(\frac{1}{4}\) of the total distance at \(60\ \text{km/h}\), and the remaining distance at \(50\ \text{km/h}\).
Find the average speed of the train.
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