Question

Поезд, двигаясь равномерно со скоростью 36 км/ч, проезжает мимо пешехода, идущего параллельно путям со скоростью 4 км/ч навстречу поезду, за 54 секунды. Найдите длину поезда в мерах

Answer 1

Скорость поезда относительно пешехода = 36+4 = 40 км/ч
Таким образом, длина поезда равна 40*54/3600=54/40=1,35 км(на 3600 мы делим из-за размерности, так как даны секунды, а нам нужны часы)

Answer 2

Problem Analysis

We are given that a train is moving at a constant speed of 36 km/h and passes a pedestrian walking parallel to the tracks at a speed of 4 km/h in the opposite direction. The train takes 54 seconds to pass the pedestrian. We need to find the length of the train.

Solution

Let's assume the length of the train is L meters.

The relative speed between the train and the pedestrian is the sum of their speeds, which is (36 + 4) km/h = 40 km/h = 40 * (1000/3600) m/s = 400/36 m/s.

The time taken by the train to pass the pedestrian is given as 54 seconds.

Using the formula distance = speed × time, we can calculate the distance covered by the train in passing the pedestrian.

The distance covered by the train is equal to the length of the train plus the distance covered by the pedestrian.

So, we have the equation: L + 400/36 × 54 = L + 600.

Simplifying the equation, we get: 400/36 × 54 = 600.

Let's calculate the length of the train.

Calculation

400/36 × 54 = 600

Simplifying the equation:

600 = 600

The equation is true, which means the length of the train is 600 meters.

Answer

The length of the train is 600 meters.