A pedestrian walking at a speed of 5.4 km / h along the platform noticed that an oncoming passenger

| February 19, 2021 | education

A pedestrian walking at a speed of 5.4 km / h along the platform noticed that an oncoming passenger train passed him in 45 seconds. What is the speed of a train if its length is 540m?

V1 = 5.4 km / h = 1.5 m / s.

L = 540 m.

t = 45 s.

V2 -?

Since a pedestrian is going to meet a moving train, the speed of the train V relative to the pedestrian will be the sum: V = V1 + V2, where V1 is the speed of the pedestrian relative to the ground, V2 is the speed of the train relative to the ground.

Let us express the travel time of the train t relative to the pedestrian using the formula: t = L / V = L / (V1 + V2).

V1 + V2 = L / t.

V2 = L / t – V1.

V2 = 540 m / 45 s – 1.5 m / s = 10.5 m / s.

Answer: the train was moving towards a pedestrian at a speed V2 = 10.5 m / s relative to the ground.



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.