Question

Прошу решить.Мост длиной 475 м поезд проходит за 45 с, а мимо дежурного по станции за 20 с.Найти скорость поезда? Найти длину поезда?

Answer 1

V=S:t=(x+475):54=vt
v=(x+475):45
t=20сек
Составим и решим уравнение:
x=20(x+475):45
x=(20x+9500):45
45x-20x=9500 
x=9500:25=380 м
Длина поезда-380м
 v=380:20=19м/сек
Переводим в км/ч(в часе 3600 сек)и получим
v=68400м//ч=68,4 км/ч
Скорость поезда-68,4км/ч

Answer 2

Problem Analysis

We are given the length of a bridge (475 m) and the time it takes for a train to pass by a stationmaster on the bridge (20 s) and a train passing by the same stationmaster on the platform (45 s). We need to find the speed of the train and the length of the train.

Solution

Let's start by finding the speed of the train.

Finding the Speed of the Train

The speed of an object can be calculated using the formula:

Speed = Distance / Time

In this case, the distance is the length of the bridge, which is given as 475 m. The time is the time it takes for the train to pass by the stationmaster on the bridge, which is given as 20 s.

Plugging in the values into the formula, we get:

Speed = 475 m / 20 s

Calculating this, we find that the speed of the train is 23.75 m/s.

Finding the Length of the Train

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

Length = Speed × Time

In this case, the speed is the speed of the train that we just calculated (23.75 m/s), and the time is the time it takes for the train to pass by the stationmaster on the platform, which is given as 45 s.

Plugging in the values into the formula, we get:

Length = 23.75 m/s × 45 s

Calculating this, we find that the length of the train is 1068.75 m.

Answer

Therefore, the speed of the train is 23.75 m/s and the length of the train is 1068.75 m.

Please let me know if you need any further clarification.