Question

два поезда движутся навстречу друг другу со скоростями 54 и 36 км/ч. пассажир находящийся в поезде замечает что 2 поезд проходит мимо него в течение 20 сек. какова длина поезда?

Answer 1

V=v1+v2=54+36=90км/ч - т.к. поезда движутся в противоположные стороны, скорости надо суммировать
90км/ч=90000/3600=25м/с - надо перевести скорость в м/с, т.к. время дано в секундах
25*20=500м - длина равна скорости умноженной на время (l=v*t)

Answer 2

Problem Analysis

We are given two trains moving towards each other with speeds of 54 km/h and 36 km/h. A passenger in one of the trains observes that the two trains pass each other in 20 seconds. We need to find the length of the train.

Solution

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

Length of the train = Relative speed × Time taken to pass

The relative speed of the two trains is the sum of their speeds since they are moving towards each other. Let's calculate the relative speed:

Relative speed = Speed of train 1 + Speed of train 2

Substituting the given values:

Relative speed = 54 km/h + 36 km/h = 90 km/h

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

Length of the train = Relative speed × Time taken to pass

Substituting the given value of the time taken to pass (20 seconds) and converting the relative speed to meters per second:

Length of the train = (90 km/h) × (1000 m/3600 s) × (20 s)

Simplifying the expression:

Length of the train = (90 × 1000 × 20) / (3600)

Calculating the length of the train:

Length of the train = 500 meters

Therefore, the length of the train is 500 meters.

Answer

The length of the train is 500 meters.