Multiple choice

A train moving at 72 km/hr crosses a bridge in 45 seconds. The length of train is 150 meters. Find the length of the bridge.

  1. 475 m

  2. 235 m

  3. 750 m

  4. 545 m

  5. 650 m
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Speed = 72 km/hr = 72 * (5/18) = 20 m/s. Total distance = Speed * Time = 20 * 45 = 900 meters. Total distance = Length of train + Length of bridge. 900 = 150 + L_bridge. L_bridge = 750 meters.

AI explanation

First convert the train's speed of 72 km/hr to m/s using the 5/18 conversion factor, yielding 20 m/s. When a train crosses a bridge, the total distance covered is the train's length plus the bridge's length, so use the formula distance equals speed multiplied by time to write 150 plus L equals 20 multiplied by 45. Solving this equation gives 150 plus L equals 900, so the length of the bridge is 750 m.

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