Determine the length of the train moving across the bridge 500 m at a speed of 15 km / h if the train passes

Determine the length of the train moving across the bridge 500 m at a speed of 15 km / h if the train passes the bridge for 1.5 minutes.

Initial data: Lm (bridge length) = 500 m; V (train speed) = 15 km / h (4.17 m / s); t (time during which the train crossed the bridge) = 1.5 minutes (90 s).

The length of the train can be expressed from the formula: (Lp + Lm) = V * t, whence Lp = V * t – Lm.

Let’s make the calculation: Lp = 4.17 * 90 – 500 = 375 – 500 <0 (in 1.5 minutes at a speed of 15 km / h, the train will not be able to pass a bridge 500 m long).