Question

В течении какого времени скорый поезд длинной в 300 м, идущий со скоростью 72 км/ч, будет проходить мимо встречного поезда длинной 600 м, идущего со скоростью 36 км/ч?

Answer 1

V1=72 км/ч=20 м/с
L1=300 м
V2=36 км/ч = 10 м/с
L2=600 м

t = (L1+L2) / (V1+V2) = (300+600)/(20+10) = 900/30 = 30 c

Answer 2

Calculating the Overtaking Time of the Trains

To calculate the time it takes for the faster train to overtake the slower train, we can use the concept of relative speed. The relative speed of the two trains is the difference between their speeds.

Given: - Length of the faster train, 300 m - Speed of the faster train, 72 km/h - Length of the slower train, 600 m - Speed of the slower train, 36 km/h

Solution

The relative speed of the two trains is the difference between their speeds, which is 72 km/h - 36 km/h = 36 km/h.

To calculate the time it takes for the faster train to overtake the slower train, we can use the formula: \[ \text{Time} = \frac{\text{Distance}}{\text{Speed}} \]

The distance the faster train needs to cover to overtake the slower train is the sum of the lengths of the two trains, which is 300 m + 600 m = 900 m.

Converting the relative speed to m/s: \[ 36 \, \text{km/h} = 36 \times \frac{1000}{3600} \, \text{m/s} = 10 \, \text{m/s} \]

Using the formula: \[ \text{Time} = \frac{900 \, \text{m}}{10 \, \text{m/s}} = 90 \, \text{s} \]

Answer

The faster train, with a length of 300 m and a speed of 72 km/h, will take 90 seconds to overtake the slower train, which has a length of 600 m and a speed of 36 km/h.