The train passes by the observer within 10 seconds, and across the 400 m long bridge within

The train passes by the observer within 10 seconds, and across the 400 m long bridge within 30 seconds. Determine train length and speed.

Data: t1 (time of movement past the observer) = 10 s; Lm (bridge length) = 400 m; t2 (time of movement on the bridge) = 30 s.

System of equations (determine the length of the train):

V = Lп / t1 (train movement past the observer).

V = (Lp + Lm) / t2 (movement on the bridge).

Lp / t1 = (Lp + Lm) / t2.

Lp / 10 = (Lp + 400) / 30 | * thirty.

3Lp = Lp + 400.

2Lp = 400 and Lp = 400/2 = 200 m.

Let’s determine the speed of the train: V = Lp / t1 = 200/10 = 20 m / s.

Check: V = (Lp + Lm) / t2 = (200 + 400) / 30 = 600/30 = 20 m / s (correct).