A train speeding at 18 km/h crosses the platform in 56seconds, but it takes 7 seconds to cross a man standing on the same platform. What is the length of the platform?
The speed of the train in m/s is 18 × (5/18) = 5 m/s. The length of the train can be obtained from the time it takes to cross the man = $5 × 7$ = 35meters. The combined length of the train and platform can be obtained from the time it takes to cross the platform, = $5 × 56 = 280$ meters. Subtracting, we get the length of the platform = 245 m.