A 130 m long train passes a cart running at a speed of 4 km/hr in the direction of the train in 8 seconds. What is the speed of the train?

Because the cart moves in the same direction as the train, the relative speed equals the train's speed minus the cart's speed. Let the train's speed be x kmph; converting the cart's speed to m/s gives a relative speed of ((x - 4) * 5/18) m/s. Using the formula time equals distance divided by relative speed, we get 130 / (((x - 4) * 5/18)) = 8, which yields x - 4 = 58.5 and gives the train's speed as 62.5 kmph.

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