Question

Мост длиной 475 м поезд проходит за 45с.С такой хе скоростью он проходит мимо дежурного по станции за 20 с. .Найдите скорось поезда..Найдите длину поезда.А. 320 м;В. 360 м;С. 300 м;D. 380 м;

Answer 1

Пусть длина поезда - х м, тогда расстояние на мосту 475+х, а скорость на мосту (475+х)/45. Скорость мимо дежурного по станции тогда: х/20
Скорости одинаковые по условию, приравняем:
(475+х) / 45 = х/20
20(475+х)=45х
9500+20х = 45х
25х = 9500
х=380
Скорость поезда тогда = (475+380)/45 = 19 м/с = 68,4 км/ч
Ответ. Длина поезда 380 м. Скорость поезда 68,4 км/ч

Answer 2

Calculating Train Speed and Length

To find the speed of the train, we can use the formula: speed = distance / time. Given that the train passes the station master in 20 seconds and the length of the bridge is 475 meters, we can calculate the speed of the train.

The time taken by the train to cross the bridge is 45 seconds, and the time taken to pass the station master is 20 seconds. We can use this information to calculate the speed of the train.

Using the formula speed = distance / time, we can calculate the speed of the train as follows:

Speed of the train = Length of the bridge / Time taken to cross the bridge

Speed of the train = 475 m / 45 s

Speed of the train = 10.55 m/s.

Finding the Length of the Train

To find the length of the train, we can use the formula: length = speed * time. Given that the train passes the station master in 20 seconds and the speed of the train is 10.55 m/s, we can calculate the length of the train.

Using the formula length = speed * time, we can calculate the length of the train as follows:

Length of the train = Speed of the train * Time taken to pass the station master

Length of the train = 10.55 m/s * 20 s

Length of the train = 211 meters

So, the length of the train is 211 meters.

Therefore, the correct option for the length of the train is not provided in the given options.