![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
A car in a straight line on a straight road, the first speed V1 driving two-thirds of the distance Then, one third of the distance is finished with the speed V2 = 20km / h. If the average speed of the car in the whole process is 28km / h, then V1 = () km / h
Physics of grade one in Senior High School: a moves in a straight line with uniform speed V1 on a straight road
A moves in a straight line at a constant speed V1 on a straight road. At a certain time, B starts from a point O directly behind a and pursues a car at a constant speed V2 (V2 > V1). After a short period of time t, C also starts from point O and pursues a car at a constant speed v2. When B and C catch up with a, they immediately turn around and return to point O, and the speed remains the same
(1) After B overtakes a, how long does it take C to overtake a?
(2) What is the time interval between B and C returning to o?
I have solved the first question in a different way
Suppose that when B starts, the distance between a and O is x0, and the time for B to catch up with a is T1, then V2 * T1 * = V1 * T1 + x0
The time for a to catch up with B is T2, then V1 * t + x0 + V1 * T2 = V2 * T2
From the meaning of the title, △ t = T1-T2 = V1 * t / (v2-v1) (correct)
The second question is how to do it according to my method. I can't understand it
According to LZ's problem-solving method, we use distance to calculate time, so I also use distance to calculate time to do the second question. B's total journey is set as S1: S1 = 2v2 * T1, C's total journey is set as S2: S2 = 2v2 * T2, then B's total movement time is T1 = S1 / V2 = 2t1 -------- 1, C's total movement time is T2 =
A and B drive to the same target from a certain place along a straight road at the same time. A moves in a uniform straight line at the speed V1 in the first half of the time and V2 in the second half of the time (V1 ≠ V2); B moves in a uniform straight line at the speed V1 in the first half of the distance and V2 in the second half of the distance (V1 ≠ V2)
A. A car arrives first B. B car arrives first C. A and B arrive at the same time D. not sure
The distance between a and B is regarded as 1. Suppose that the time taken by a from a to B is T1, and the time taken by B from a to B is T2, then the time taken by a from a to B is T1 = 2v1 + V2, and the time taken by B from a to B is T2 = 12v1 + 12V2 = V1 + v22v1v2
The speed of a is twice that of B, and the movement time of a is three times that of B. then the distance that a passes through is ()
A. 2 times B. 3 times C. 6 times D. 5 times
∵ V A = 2V B, t a = 3T B, ∵ s a s b = v a t a v b t b = 2V B × 3T b v b t b = 6
RELATED INFORMATIONS
- 1. A and B start from a and return to B at the same time. They meet B at 45km away from B. the speed ratio of a and B is 3:2. How many kilometers does B walk when they meet?
- 2. A and B start from a to B at the same time. The speed of a is 3 / 5 of that of B. when B arrives at the ground, he returns immediately and meets a on the way A and B start from a to B at the same time. The speed of a is 3 / 5 of B's speed. When B returns to the ground immediately, he meets a on the way. He only knows that it takes 60 minutes for a and B to go back and forth between AB and how long does it take each
- 3. On a main highway, there are two places a and B which are 480 meters apart. The fast and slow cars run from each other at the same time. They meet in six hours. The speed ratio of the fast and slow cars is 11:9. What's the speed of the two cars?
- 4. Party A and Party B go from place a to place B at the same time, and Party A goes to place B after 10 hours, which takes 4 hours more than Party B. It is known that the speed difference between the two is 5 kilometers per hour How many kilometers per hour? The solution of the equation
- 5. A and B set out from a to B at the speed of 4 kilometers per hour at the same time. After walking 2.5 kilometers, a returned to a to pick up the documents. He rushed to a at the speed of 6 kilometers per hour. After getting the documents, he still chased b back at the speed of 6 kilometers per hour. As a result, they arrived at B at the same time. It is known that a delayed 15 minutes in the office to pick up the documents, so we can find the distance between a and B
- 6. A and B are going from AB to ab at the same time. A arrives at the destination in 3 hours, and B is 20 kilometers away from the destination. It is known that the speed ratio of a and B is 3:2 to find the distance between the two places
- 7. The passenger car and the freight car leave from a and B at the same time. The passenger car runs 50km per hour, and the speed of the freight car is 80% of that of the passenger car. After meeting, the passenger car continues to travel for 3.2 hours to reach B. how many kilometers are there between a and B?
- 8. A and B set out from a to B at the same time, 26km away. A rode a bicycle and B walked. It is known that a's speed is faster than B's A and B set out from place a to place B 26km away at the same time. A rides a bicycle and B walks. It is known that a's speed is 1km / h faster than twice that of B. after a arrives at place B, he immediately returns from place B. on the way, he meets B. The time from their departure is 4 hours. Q: what are their respective speeds? How far is the meeting point from place B?
- 9. A goes to school on foot at the speed of 4 kilometers per hour, B starts from the same place by bike 4 hours later than a, B travels 12 kilometers per hour, B______ You can catch up with a in an hour
- 10. The distance between a and B is 800 kilometers. The two cars are facing each other. The speed ratio of a and B is 6:5. When they meet, how many kilometers do the two cars walk? Detailed, quick!
- 11. A takes one fifth more distance than B, while B takes one eighth more time. The speed ratio of a and B is ()
- 12. At a certain time when a and B are competing on a straight road, B is at L1 = 11m in front of a, and B's speed v b = 600m. If a is doing well, B will be able to do well Acceleration, acceleration a = 2m / S ^ 2, B car speed unchanged, regardless of car length (1) After how long, the distance between workshop a and workshop B is the largest, and what is the maximum distance? (2) Can car a overtake car B at the terminal? Urgent. Can we solve it today? The speed of vehicle B is 60m / s, and that of vehicle a is 50M / s. at this time, vehicle B is still 600m away from the finish line Why is the distance the largest at the same speed
- 13. When a and B students come home from school, a has to walk 15 more ways than B, while B takes 111 less time than A. what is the speed ratio of a and B students to go home?
- 14. Xiaoming and Xiaofang start from home to school respectively. Xiaoming takes 15 more miles than Xiaofang, and Xiaofang takes 18 more time than Xiaoming. So the speed ratio of Xiaoming and Xiaofang is () A. 5：8B. 8：5C. 27：20D. 16：15
- 15. A, B two people each walk a section of road, they use the time ratio is 4:5, the speed ratio is 5:3, then they walk the distance ratio is? It's urgent! There is another question. The sum of the two simplest fractions with the same denominator is 9 / 10. Their molecular ratio is 7:11. The two fractions are () and ()
- 16. A and B set out at the same time from a and B which are 2000 meters apart. They met each other four minutes later. It is known that B's speed is 5 meters per second, so we can find the speed of A
- 17. A and B two cars from a, B two cities at the same time, 10 hours meet, the speed ratio of the two cars is 3:2, when a car arrives at a city, B car how many hours to arrive at B city?
- 18. Party A and Party B are walking towards each other in two places at the same time. They meet in 8 hours. If they reduce their speed by 3 kilometers per hour and meet in 10 hours, find the distance between the two places
- 19. A. The distance between B and B is 600 kilometers. A and B vehicles are facing each other at the same time and meet each other in 5 hours. It is known that the speed of a vehicle is 3 / 5 of that of B vehicle. Then the speed of a vehicle is () km per hour, and that of B vehicle is () km per hour?
- 20. There are m tons of coal in the canteen, and N tons of coal are planned to be used. In fact, 2 tons of coal are saved every day. How many days will the canteen use more coal?