Question

Два поезда двигались на встречу друг другу по параллельным путям. Один со скоростью 50 км/ч ,а второй со скоростью 70 км/ч. Пассажир второго поезда заметил, что первый поезд прошёл мимо него за 6 сек. Какова длина поезда?

Answer 1

S=vt
S- длина первого поезда, t=6 сек.
Второй движется относительно первого со скоростью (50+70) км/ч.
v=v₁+v₂=50км/ч+70 км/ч=120 км/ч=120 000/3600 м/=200/6 м/сек
S=(200/6)·6=200 м
О т в е т. 200 м

Answer 2

Problem Analysis

We are given two trains moving towards each other on parallel tracks. The first train is moving at a speed of 50 km/h, and the second train is moving at a speed of 70 km/h. The passenger in the second train notices that the first train passes by in 6 seconds. We need to find the length of the first train.

Solution

To find the length of the first train, we can use the formula:

Length = Speed × Time

Let's calculate the length of the first train using this formula.

Calculation

Given: - Speed of the first train = 50 km/h - Speed of the second train = 70 km/h - Time taken for the first train to pass the second train = 6 seconds

To calculate the length of the first train, we need to convert the speed from km/h to m/s and the time from seconds to hours.

Converting the speed of the first train from km/h to m/s: - Speed of the first train = 50 km/h = (50 × 1000) m/3600 s = 50000/3600 m/s ≈ 13.89 m/s

Converting the speed of the second train from km/h to m/s: - Speed of the second train = 70 km/h = (70 × 1000) m/3600 s = 70000/3600 m/s ≈ 19.44 m/s

Converting the time taken for the first train to pass the second train from seconds to hours: - Time = 6 seconds = 6/3600 hours ≈ 0.00167 hours

Now, we can calculate the length of the first train using the formula:

Length = Speed × Time

Length = (13.89 m/s + 19.44 m/s) × 0.00167 hours

Length ≈ 0.03333 km

Answer

The length of the first train is approximately 0.03333 km.

Explanation

When two trains are moving towards each other, the relative speed between them is the sum of their individual speeds. In this case, the relative speed is 13.89 m/s + 19.44 m/s = 33.33 m/s. The time taken for the first train to pass the second train is 6 seconds. Multiplying the relative speed by the time gives us the length of the first train, which is approximately 0.03333 km.