When an object moves in a straight line in a period of time, the velocity V1 in the first half of the time is 5 m / s, and the velocity V2 in the second half of the distance is 3 M / s What's the average speed of this object over the whole distance

Suppose the total distance is 2S, then the first half of the time T1 = s / V1 = s / 5m / s, the second half of the time T2 = s / V2 = s / 3m / s 〈 average speed (V above write a horizontal) = s total / T total = s total / (T1 + T2) = 2S / (s / 5 + S / 3) = 2S / (8s / 15) = 15s / 4 = 3.75m/s

RELATED INFORMATIONS

1. When someone is riding a bicycle, the average speed on the uphill is 3m / s, and the average speed on the downhill is 5m / s
2. A's speed is 5 m / s, B's speed is 3 M / s, in the same direction, if a let B for 4 s first, how many seconds does a run to catch up with B?
3. The width of a river is 100 m. The speed of the ship in still water is 5 m / s. The speed of the current is 3 M / s 1. How to cross the river in the shortest time 2. How to cross the river with the shortest displacement Is it perpendicular to the river bank?
4. One student finished half of the course at 3m / s, and immediately finished the other half at 5m / s______ m/s．
5. 1. The original price of a garment is 300 yuan, now the price is increased by 20%, and then the price is reduced by 20%. What is the original price? 2. The original price of a garment is 300 yuan, now the price is increased by 20%, 1. The original price of a piece of clothing is 300 yuan, now the price is increased by 20%, and then the price is reduced by 20%. What is the original price? 2. The original price of a piece of clothing is 300 yuan, now the price is increased by 20%, and then the price is reduced by 20%. What is the current price? When answering, mark the question
6. There are 1g, 2G, 4G, 8g and 15g weights. How many weights should be used to weigh 36g items on the balance at a time? Which weights are they?
7. The two diagonal lines AC and BD of trapezoidal ABCD intersect at O. it is known that the area of triangle ABO and BCO are 10 and 15 respectively. What is the area of trapezoidal ABCD in square centimeter
8. Fill in the blanks in Senior High School Biology Is there such a book that is full of blank questions about book knowledge
9. It is known that in the trapezoid ABCD, ad ‖ BC, e and F are the midpoint of AB and CD respectively, connecting EF. Please prove the triangle median theorem according to the method
10. What is cosx + 6x, odd or even
11. If the speed in the first half of the journey is 5m / s, and the speed in the second half of the journey is 3m / s, the average speed of the whole journey can be calculated In a hurry
12. The width of the river is 300 m, the flow velocity is 3 M / s, and the velocity of the boat in still water is 5 m / s, Q: (1) what is the shortest time to cross the river? Where can I get to the other bank? (2) Where should the bow of a boat cross the river on the shortest voyage? What is the crossing time?
13. One student finished half of the course at 3m / s, and immediately finished the other half at 5m / s______ m/s．
14. If the average speed of a moving object in the first second is 3m / s, the average speed in the second and third seconds is 6m / s, and the average speed in the fourth second is 5m / s, then the average speed of the object in the first two seconds is? The average speed in the whole time is?
15. A car stops and starts to run at 3 meters per second, when a bicycle comes at a constant speed of 6 meters per second How long does it take for the car to catch up with the bicycle? What is the distance between the two cars?
16. A car moves forward at a constant speed of 10m / s. after braking, the acceleration is 2.5m/s and the displacement within 3S
17. When a car moves forward at a speed of 10m / s and the acceleration is 2.5m/s2 after braking, what is the displacement in 3S? What is the displacement within 10 seconds after braking?
18. The car starts to brake at the speed of 10m / s, the acceleration is 2m / S2, and the displacement ratio of 3S, 2S and 1s before stopping is calculated
19. The average speed in the third second is 9 m / s. find (1) the acceleration of the uniform deceleration of the car (2) the displacement of the car in 10 s
20. When a bus comes into the station, it starts to brake and make a uniform deceleration linear motion. The displacement in the first second and the second second is 9m and 7m respectively, then the displacement in the sixth second after braking is () A. 20 mB. 24 mC. 25 mD. 75 m