Question

Відстань між двома містами 180 км. Першу третину цього шляху автомобіль рухався зі швидкістю 60 км/год, потім автомобіль зробить зупинку на 45 хв, а решту 2/3 шляху проїхав із середньою швидкістю 45 км/год. Яка середня швидкість автомобіля на всьому шляху?​

Answer 1

Calculation of Average Speed

To calculate the average speed of the car for the entire journey, we need to consider the different segments of the trip and their respective durations.

1. First segment: The car travels one-third of the total distance at a speed of 60 km/h. 2. Second segment: The car makes a stop for 45 minutes. 3. Third segment: The car travels the remaining two-thirds of the distance at a speed of 45 km/h.

Let's calculate the average speed step by step:

1. Calculate the distance covered in the first segment: - Total distance: 180 km - One-third of the distance: 180 km * (1/3) = 60 km

2. Calculate the time taken for the first segment: - Speed: 60 km/h - Time = Distance / Speed = 60 km / 60 km/h = 1 hour

3. Calculate the time taken for the second segment: - The car stops for 45 minutes, which is equivalent to 0.75 hours.

4. Calculate the distance covered in the third segment: - Total distance: 180 km - Two-thirds of the distance: 180 km * (2/3) = 120 km

5. Calculate the time taken for the third segment: - Speed: 45 km/h - Time = Distance / Speed = 120 km / 45 km/h = 2.67 hours

6. Calculate the total time taken for the entire journey: - Total time = Time taken for the first segment + Time taken for the second segment + Time taken for the third segment - Total time = 1 hour + 0.75 hours + 2.67 hours = 4.42 hours

7. Calculate the average speed: - Average speed = Total distance / Total time = 180 km / 4.42 hours ≈ 40.72 km/h

Therefore, the average speed of the car for the entire journey is approximately 40.72 km/h.