Question

Из двух городов,расстояние между которыми 800км,одновременно навстречу друг другу выехали два поезда и встретились через 5 часов. Скорость первого поезда 75км/час. С какой скоростью ехал второй поезд? На каком расстоянии друг от друга были поезда через 3 часа после выхода.

Answer 1

1)  800:5=160(км/ч)-скорость сближения поездов
2)  160-75=85(км/ч)-скорость второго
3)  75*3=225(км)-прошел первый за 3 часа
4)   85*3=255(км)-прошел второй за 3 часа
5)  800-225-255=320(км)-расстояние между ними через 3 часа

Answer 2

Problem Analysis

We have two trains traveling towards each other from two cities that are 800 km apart. The first train has a speed of 75 km/h. We need to find the speed of the second train and the distance between the trains after 3 hours.

Solution

To find the speed of the second train, we can use the formula:

Speed = Distance / Time

Let's calculate the speed of the second train first.

The first train travels for 5 hours and covers a distance of 75 km/h * 5 h = 375 km.

Since the two trains meet after 5 hours, the second train also travels for 5 hours. The total distance covered by both trains is 800 km. Therefore, the distance covered by the second train is 800 km - 375 km = 425 km.

Now, let's calculate the speed of the second train:

Speed of the second train = Distance / Time = 425 km / 5 h = 85 km/h

So, the speed of the second train is 85 km/h.

Next, let's calculate the distance between the trains after 3 hours.

The first train has a speed of 75 km/h and travels for 3 hours. Therefore, the distance covered by the first train is 75 km/h * 3 h = 225 km.

The second train has a speed of 85 km/h and also travels for 3 hours. Therefore, the distance covered by the second train is 85 km/h * 3 h = 255 km.

The total distance between the trains after 3 hours is the difference between the distance covered by the first train and the distance covered by the second train:

Distance between the trains after 3 hours = 255 km - 225 km = 30 km

So, the distance between the trains after 3 hours is 30 km.

Conclusion

The second train traveled at a speed of 85 km/h, and the distance between the trains after 3 hours was 30 km.