A train is moving at a speed of 85m/s. It takes 7 seconds to cross a jeep that is travelling in the opposite direction at a speed of 83m/s. What is the length of the train?
The distance to be covered is equal to the length of the train. This distance has to be covered at a net relative speed equal to the sums of the speeds of the jeep and the train, so v = 85 + 83 = 168. The length of the train will be time × speed = $7 × 168$ = 1176meters.