A train with a length of 300 m moves evenly at a speed of 20 m / s. He crosses the bridge in 1.5

A train with a length of 300 m moves evenly at a speed of 20 m / s. He crosses the bridge in 1.5 minutes. What is the length of the bridge?

Given:

L = 300 meters – train length;

v = 20 meters per second – train speed;

t = 1.5 minutes = 90 seconds – the time it takes for the train to completely pass the bridge.

It is required to determine S (meters) – the length of the bridge.

The bridge is considered to be passed when the rear carriage of the bridge has completely passed it. Then, if the length of the train is S, then the train must travel a total distance equal to S + L. Based on this:

S + L = v * t;

S = v * t – L = 20 * 90 – 300 = 1800 – 300 = 1500 meters.

Answer: the length of the bridge is 1500 meters.