Question

по двум параллельным железнодорожным путям навстречу друг другу движутся равномерно два поезда: грузовой - длиной 630 метров со скоростью 48 км/ч и пассажирский длиной 120 метров со скоростью 102 км/ч. В течение какого времени один поезд проходит мимо другого?

Answer 1

учитывая, что поезда имеют размеры (начало и конец) движение мимо встречного будет длиться 120+630 =750 м = 0.75 км

встречная скорость 48+102= 150 км/ч

тогда время движения МИМО 0.75 км / 150 км/ч *60   =0.3 мин = 18 с

Answer 2

Problem Analysis

We are given two trains moving towards each other on parallel railway tracks. The first train is a freight train with a length of 630 meters and a speed of 48 km/h. The second train is a passenger train with a length of 120 meters and a speed of 102 km/h. We need to determine the time it takes for one train to pass the other.

Solution

To find the time it takes for one train to pass the other, we can use the concept of relative velocity. The relative velocity is the difference between the velocities of the two trains.

Let's calculate the relative velocity:

- Velocity of the freight train = 48 km/h - Velocity of the passenger train = 102 km/h

The relative velocity is the sum of the velocities of the two trains:

Relative velocity = Velocity of the freight train + Velocity of the passenger train

Now, let's calculate the time it takes for the trains to pass each other. We can use the formula:

Time = Distance / Relative velocity

The distance is the sum of the lengths of the two trains:

Distance = Length of the freight train + Length of the passenger train

Let's substitute the values and calculate the time:

Calculation

Length of the freight train = 630 meters Length of the passenger train = 120 meters

Distance = 630 meters + 120 meters = 750 meters

Velocity of the freight train = 48 km/h Velocity of the passenger train = 102 km/h

Relative velocity = 48 km/h + 102 km/h = 150 km/h

Converting the relative velocity to meters per second:

Relative velocity = 150 km/h * (1000 m / 1 km) * (1 h / 3600 s) = 41.67 m/s

Time = Distance / Relative velocity = 750 meters / 41.67 m/s ≈ 18 seconds

Answer

The freight train will take approximately 18 seconds to pass the passenger train.

Note: The above calculation assumes that the trains start passing each other when their fronts are aligned and end passing each other when their rears are aligned.