SCIENCE(PHYSICS)
posted by YASH .
A TRAIN IS MOVING ON A STRAIGHT TRCK AND TRAVELS AT A SPEED OF 72KM/HR AND PASSES A POLE BIN 3 SECONDS. FIND THE TJME TAKEN TO PASS A BRIDGE OF LENGTH 540m

It must be a rather short train if it passes a pole in three seconds.
72 km/h = 20 m/s. The length of the train must be
L = 20 m/s * 3 s = 60 meters
To cross a bridge 540 m long, you have to add the times it takes the engine to cross (540/20 = 27 seconds) and the three seconds needed for the rest of the train to reach the end. That is a total of 30 seconds.