Question

Город В находится в 63 км от города А ниже по течению реки. Теплоход плывёт из А в В и обратно. На сколько больше времени понадобится ему на обратный путь, если собственная скорость теплохода 32км/ч, а скорость течения 4 км/ч?

Answer 1

1. 32 + 4 = 36 (км/ч) - скорость по течению
2. 63: 36 = 1,75 (ч)  - время из А в В
3. 32 - 4 = 28 (км/ч) - скорость против течения
4. 63 : 28 = 2,25 (ч) - время из В в А
5. 2,25 - 1,75 = 0,5 (ч)

Answer 2

Problem Analysis

We are given that City B is located 63 km downstream from City A along a river. A boat travels from City A to City B and back. We need to determine how much longer it will take for the boat to return from City B to City A if the boat's speed is 32 km/h and the river's current speed is 4 km/h.

Solution

To solve this problem, we need to consider the effect of the river's current on the boat's speed. When the boat is traveling from City A to City B, the current helps the boat move faster. However, when the boat is returning from City B to City A, the current opposes the boat's motion, making it slower.

Let's calculate the time it takes for the boat to travel from City A to City B and from City B to City A separately.

Time to travel from City A to City B

The boat's speed relative to the ground is the sum of its own speed and the speed of the river's current. Therefore, the boat's speed from City A to City B is 32 km/h + 4 km/h = 36 km/h.

To calculate the time it takes for the boat to travel from City A to City B, we divide the distance between the two cities by the boat's speed:

Time = Distance / Speed

Time = 63 km / 36 km/h

Time = 1.75 hours

Time to travel from City B to City A

The boat's speed relative to the ground when traveling from City B to City A is the difference between its own speed and the speed of the river's current. Therefore, the boat's speed from City B to City A is 32 km/h - 4 km/h = 28 km/h.

To calculate the time it takes for the boat to travel from City B to City A, we divide the distance between the two cities by the boat's speed:

Time = Distance / Speed

Time = 63 km / 28 km/h

Time ≈ 2.25 hours

Conclusion

Therefore, it will take the boat approximately 2.25 hours to return from City B to City A, which is 0.5 hours longer than the time it took to travel from City A to City B.

Please note that the calculations provided above are based on the given information and assumptions.