Question

The speed of train is 72 km/hr the length of the train is 400 metres . how long will it take to cross a standing train of length 100 metres

Answer 1

Given;

• speed of Train = 72 km/h
• thus to convert it into m/s;

$72 \times \frac{5}{18} \\ 4 \times \frac{5}{1} \\ = 20 \: m/s$

• For a train to completely cross another train ;
• The end point of first train should cross the starting point of another train

Thus by this logic total dist;

• 400 + 100
• 500 m

Thus we know that;

$s \: = \frac{d}{t}$

$t \: = \frac{d}{s}$

$t = \frac{500}{20} \\ t = \frac{50}{2} \\ t = 25 \: seconds$

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