Question

Решите задачу. из деревни петровка в село михайловское,расстояние до которого 15км, в 8 часов утра вышел пешеход , а в 12 часов из деревни в том же направлении выехал велосипедист. догонит ли велосипедист пешехода , если пешеход идёт со скоростью 3км/ч,а велосипедист едет со скоростью 12км/ч?

Answer 1

12-8=4( ч)разность во времени
3×4=12(км)прошёл за 4 часа
15-12=3(км)осталось,тоесть остался 1 час
12×1=12(км)проедет за 1 час
Ответ:нет не догонит

Answer 2

Problem Analysis

We are given that a pedestrian starts walking from the village of Petrovka towards the village of Mikhaylovskoye at 8 AM. At 12 PM, a cyclist starts cycling from the village of Petrovka towards the same destination. We need to determine if the cyclist will catch up to the pedestrian.

Solution

To solve this problem, we need to compare the distances covered by the pedestrian and the cyclist over the given time period.

Let's calculate the distance covered by the pedestrian from 8 AM to 12 PM (4 hours): Distance covered by the pedestrian = Speed of the pedestrian * Time = 3 km/h * 4 h = 12 km

Now, let's calculate the distance covered by the cyclist from 12 PM to the time when they catch up to the pedestrian: Distance covered by the cyclist = Speed of the cyclist * Time

To find the time it takes for the cyclist to catch up to the pedestrian, we can use the formula: Time = Distance / Relative Speed

The relative speed is the difference between the speeds of the cyclist and the pedestrian: Relative Speed = Speed of the cyclist - Speed of the pedestrian

Substituting the given values: Relative Speed = 12 km/h - 3 km/h = 9 km/h

Now, let's calculate the time it takes for the cyclist to catch up to the pedestrian: Time = Distance / Relative Speed = 15 km / 9 km/h

To determine if the cyclist catches up to the pedestrian, we need to compare the time it takes for the cyclist to catch up to the pedestrian with the time the cyclist starts cycling (12 PM). If the time it takes for the cyclist to catch up is less than 4 hours, then the cyclist will catch up to the pedestrian.

Let's calculate the time it takes for the cyclist to catch up to the pedestrian: Time = 15 km / 9 km/h = 1.67 hours

Since 1.67 hours is less than 4 hours, the cyclist will catch up to the pedestrian.

Conclusion

The cyclist will catch up to the pedestrian if the pedestrian is walking at a speed of 3 km/h and the cyclist is cycling at a speed of 12 km/h. The cyclist will catch up to the pedestrian in approximately 1.67 hours after the cyclist starts cycling at 12 PM.