Xiaohong has measured that her average walking speed is 1.2m/s, km / h; her home is 720m away from the school, so she has to walk at least 20 minutes in advance to avoid being late Xiaohong has measured that her average walking speed is 1.2m/s, km / h; her home is 720m away from school, so she has to leave home at least min in advance to avoid being late

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• 1. Xiao Ming walks home at the speed of 4 kilometers per hour along a bus route after school. Along the way, one bus overtakes him from behind every 9 minutes, and another bus comes face to face every 7 minutes. If the bus keeps running at the same speed at the same time interval, the bus will run at the same time interval______ Give out a car
• 2. Three hours after the truck left the station at a speed of 30 km / h, a motorcycle chased the truck at a speed of 50 km / h. how many hours can I catch up with the truck?
• 3. From place a to place B, it takes 3.6 hours for someone to walk more than by bus. It is known that the walking speed is 8 kilometers per hour, and the bus speed is 40 kilometers per hour. How many kilometers are there between place a and place B?
• 4. From place a to place B, it takes 1.4 hours for someone to walk more than by bus. It is known that the walking speed is 5 kilometers per hour, and the bus speed is 40 kilometers per hour. Suppose that the distance between place a and place B is x kilometers, then the equation is________________ .
• 5. Lili's father goes to work by bike. It takes 45 minutes to get to work. It takes 15 minutes by bus (bus: 60 km / h). What do you do?
• 6. There are two ways for someone to go out from his place of residence, one is to go by bike, the other is to go by bus. Obviously, the speed of bus is faster than that of bicycle, but there is a waiting time (waiting time can be regarded as fixed). In any case, he always adopts the best way to spend the least time. The table on the next page shows that he arrives at a, B and C How long does it take for him to get to 8 kilometers away from his home? The best distance between the destination and the place of residence is a 2 km 12 min, B 3 km 15.5 min, C 4 km 18 min
• 7. The distance between a and B is 21km. After a starts for 1.5h, B starts again. A is in the back, B is in the front, walking in the same direction. A rides 8km every hour, B walks every hour 5km, how many hours after a starts to catch up with B?
• 8. The distance between Party A and Party B is 60km. A car passes one third of the whole journey at an average speed of 40kmh, and the remaining two thirds of the journey takes 2.5h What's the average speed of the car in the second third of the distance? 2. The average speed of the car in the whole journey?
• 9. The distance between a and B is 40km. A starts for 1.5h and then B starts. A is behind and B is in front. They walk in the same direction. The speed of a is 8km / h and that of B is 6km / h. how many hours after a start, can a catch up with B?
• 10. If a car drives from a to B at a speed of 60km / h, and it returns from B to a at a speed of 40km / h, what is the average speed of the car How many km / h
• 11. In response to the school's "energy conservation and environmental protection" initiative, Xiao Lin changed to go to school by bike instead of by bus. The distance between Xiao Lin's home and school is 3km, and he can get to school by bike in 10min? (2) If the average resistance of the bicycle is 80N, how much work has he done to overcome the resistance during this period of riding?
• 12. After the meeting, the two cars were still moving at the same speed. When they were 196 kilometers apart, the bus stopped running 3-5, 80% of the freight cars in the whole process How many hours does the complete journey take
• 13. It takes 6 hours for a bus to travel and 8 hours for a truck to complete the whole journey. When the two cars meet, it's just the distance between a and B Please write down the reason for the last step in detail. It's best to solve it in a few minutes
• 14. It takes 8 hours for the passenger car to complete the whole journey, and 12 hours for the freight car to complete the whole journey. When the two cars meet, they are separated from each other in the whole journey At 1:20 a.m., the bus was 260 meters long. How many kilometers are there between a and B?
• 15. A bus and a freight car leave from ab at the same time and meet each other after 8 hours A passenger car and a freight car leave from ab at the same time. After 6 hours of meeting, both cars continue to move at the same speed. After 4 hours, the passenger car arrives at B. at this time, the freight car is 188 kilometers away from A. how many kilometers is the distance between a and B
• 16. A passenger car and a freight car leave from a and B at the same time. After six hours of meeting, the two cars continue to move forward at the same speed. After four hours of bus B, the freight car is 188 kilometers away from A. how many kilometers is the distance between AB and a?
• 17. The passenger car and the freight car leave from a and B and meet each other in 5 hours. The latter two cars run for 3 hours respectively. The passenger car is 180 km away from B and the freight car is 210 km away from a A. B how many kilometers are there? Is that ok? Suppose the speed of the bus is x, the train is 5x + 5Y = 8x + 180, and the train is 5x + 5Y = 8y + 210
• 18. At the same time, the bus and the freight car leave from AB for 5 hours, and then the two cars go on for 3 hours. At this time, the bus is 180 meters away from B, and the freight car is 210 meters away from a A passenger car and a freight car leave from ab at the same time and meet each other in 5 hours. After meeting, the two cars continue to move forward for 3 hours. At this time, the passenger car is 180 kilometers away from B and the freight car is 210 kilometers away from A. how many kilometers is the distance between AB and ab? To process and detailed description, urgent need!!!!!!!!!!
• 19. The distance between city a and city B is 480 meters. A truck and a bus meet 4 hours after driving from city a and city B respectively. The speed ratio of truck and bus is 3:5 What are the speeds of freight cars and passenger cars?
• 20. On the map with a scale of 1:6000000, the distance between AB and ab is 15cm, and the two vehicles start from each other at the same time, I want to meet you in six hours. It is known that the speed of car a is seven eighths of that of car B. how many kilometers does car a travel per hour