Question

A train 180 m long, crosses a 240m long bridge in 12 seconds.
Find the speed of the train in km/h.

Answer 1

Length of the first train=180m

Time taken by the train to cross the man standing on the platform=12s

Speed of the first train= 12/180

=15m/s

Speed of the second train= 2/3×15

=10m/s

Relative speed=15+10

=25m/s

Let the length of the train be y metres.

Distance=Speed×time

y+180=25×12

y+180=300

y=300-180

y=120

So, the length of the second train=120m