The car runs at a speed of 15 meters per second, and starts to brake from a certain moment. After braking, the car moves in a straight line with uniform deceleration, and the acceleration is 6 meters per square second When the car runs at a speed of 15 meters per second, it starts to brake from a certain moment, and then makes a uniform deceleration linear motion. If the acceleration is 6 meters per square second, the displacement of the car in 3 seconds after braking is?
This problem is a bit insidious. If we use the displacement formula directly, it is wrong. Because the speed is - 3m / s in 3 seconds, the car has stopped. So we use the formula s = ((V beginning) ^ 2 - (V end) ^ 2) / 2A = 18.75m
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- 1. When the car runs at a constant speed V, the acceleration after braking is a, and it moves in a straight line at a constant deceleration, the displacement after T & nbsp; seconds is () A. Vt-at22b. V22ac. - vt + at22d. Cannot be determined
- 2. The car runs on the road at a speed of 10m / s, and then decelerates at a speed of 2m / S 2 after braking. The speed at the end of 4S and the displacement of the car in 8s after braking are calculated
- 3. When the acceleration is 4m / S & sup2; after emergency braking at the speed of 10m / s, then () A. the displacement is 12m within 2S after braking The displacement of B is 12.5m within 2S after braking C. The displacement within 3S after braking is 12m D. the displacement within 3S after braking is 12.5m
- 4. The acceleration of a car traveling at 10m / s after emergency braking is 6m / S2, and the displacement within 5.0s after braking is calculated Please answer the questions quickly
- 5. When a car is running at a constant speed of 20 m / s and reaches an acceleration of 4 m / S2 after emergency braking, what is the displacement within 8 s after braking? Such as the title
- 6. The acceleration of a car traveling at 10m / s after emergency braking is 4m / S ^ 2. How much displacement of the car within 2S after braking and how much displacement is within 3S after braking?
- 7. After closing the throttle, a car slides down a slope from the top with an initial speed of 3m / s, and the speed at the bottom just becomes zero. If the car slides down from the top with an initial speed of 5m / s after closing the throttle, the speed at the bottom will be () A. 1m/sB. 2m/sC. 3m/sD. 4m/s
- 8. The acceleration of the car running at 12m / S is 5m / S ^ 2 after emergency braking, and the displacement within 6S after ball braking
- 9. When the car is running at the speed of 8m / s and the acceleration after emergency braking is 6m / S2, what is the displacement within 4S after braking? What is the speed at the end of 4 seconds?
- 10. It takes 5 minutes for a train to go from standstill to 100 km / h, and 10 seconds for a car
- 11. If the two physics move in a straight line at a constant speed, the speed of a is 2m / s, and the speed of B is 3m / s, then the ratio of the distance they pass and the time they spend is correct A. If the time ratio is 1:1, the distance ratio is 2:3 B. if the time ratio is 1:1, the distance ratio is 3:2 C. If the distance ratio is 1:1, the time ratio is 3:2 D. if the distance ratio is 1:1, the time ratio is 2:3
- 12. On the straight road, car a and car B move in the same direction. Car B moves in a straight line at a speed of 3 M / s. when car B is 4 m in front of car a, car a will leave the road At rest, it starts to make a uniform acceleration linear motion with an acceleration of 2 m / S2. When car a catches up with car B, it immediately makes a uniform deceleration linear motion with an acceleration of - 4 m / S2. How long will it take car B to catch up with car a again?
- 13. A and B start from the same place along the same road at the same time. A's speed is 2m / s, B's speed is 3m / s, after 5 minutes How far away are they from each other? There are two kinds of solutions, both written out, and there must be a process
- 14. The speed of a is 2 m / s, and that of B is 3 M / s. The ratio of time they take to pass the same distance is______ The ratio of the distance traveled in the same time is______ .
- 15. The speed of a is 2 m / s, and that of B is 3 M / s. The ratio of time they take to pass the same distance is______ The ratio of the distance traveled in the same time is______ .
- 16. For an object moving in a straight line with uniform deceleration, the velocity at a certain moment is 8m / s, and after 1s, the velocity becomes 4m / s, then the displacement of the object passing through in 1s
- 17. When an object moves in a straight line with uniform speed change, the speed is 4m / s at a certain moment, and becomes 10m / s after 1s. What is the acceleration of the object? The answer is that when the initial velocity direction is positive, there are two cases of the end velocity. If the initial velocity is negative, the end velocity is positive, and 10 minus 4 = 14, the acceleration will be 14m / s Square, there will be one more case The acceleration is - 6m / s Square.
- 18. When an object moves in a straight line with constant speed, its velocity is 3 m · S-1 at a certain time, and 9 m · S-1 after 1 s A. The displacement may be less than 5MB. The displacement may be less than 3mc. The acceleration may be less than 11m · s-2d. The acceleration may be less than 6m · S-2
- 19. When a particle with uniform acceleration passes through three points a, B and C continuously, it is known that ab = BC, and the average velocity of the particle in AB section is 3M/ When a particle moving in a straight line with uniform acceleration passes through three points a, B and C continuously, it is known that ab = BC, and the average velocity of the particle in AB section is 3m / s, and the average velocity in BC section is 6m / s, then the velocity of the particle in B is ()
- 20. When an object moving in a straight line with uniform acceleration passes through points a, B and C in turn, the displacement SAB = SBC. It is known that the average velocity of the object in AB section is 1m / s, and the average velocity in BC section is 3m / s, then the instantaneous velocity of the object at point B is () A. 1.5m/sB. 2m/sC. 5m/sD. 2.5 m/s