Physics 20 Acceleration Worksheet

Transcription

1 Physics 20 Acceleration Worksheet 1. A racecar reaches the straightaway on the race track going 140km/hr and accelerates at a rate of 3.5m/s 2 for 6.2 seconds. a) what is the car s initial speed in m/s? 39m/s b) What is the car s speed at the end of the 6.2 seconds? 61m/s c) How far did the car travel in that time? 3.1x10 2 m 2. Mervin the Menace drops a waterbomb from his apartment window. It hits the ground 4.25 seconds later. How far off the ground is Mervin s apartment window? 88.6m 3. A fighter jet covers a distance of 895m while accelerating from 22m/s to 35m/s. How long (in seconds) did this take to happen? 31s 4. A proton is accelerated in a linear accelerator. If the accelerator is 0.80km long, how long does it take to get the proton from rest to 2.5 x 10 8 m/s? 6.4x10-6 s 5. A car is coasting backwards down a hill at 3.0m/s when the driver get the engine started. After 2.5s the car is moving at +4.5m/s. What is the average acceleration of the car? +3.0m/s 2 6. Using the graph at right answer the following questions. a) during which time interval or intervals is the speed constant? 5-15s and 20-29s b) During which time interval or intervals is the train s accleration positive? 0-5s c) During which interval or intervals is its acceleration less than zero? 15-20s and 29-40s d) During which interval is the acceleration most negative? 15-20s 7. For the same graph, find the average acceleration during the given time intervals. a) 0 to 5s (+2.0m/s 2 ) b) 0 to 10s (1.0m/s 2 ) c) 15 to 20s (-1.2m/s 2 ) d) 0 to 40s (0m/s 2 ) 8. A golf ball rolls up a hill toward a hole. a) if it starts with a velocity of +2.0m/s and accelerates at a constant rate of -0.50m/s 2, what is its velocity after 2.0s? +1.0m/s b) If the acceleration occurs for 6.0s, what is the final velocity? -1.0m/s 9. A car slows from 22m/s to 3m/s with a constant acceleration of 2.1m/s 2. How long does this require? 9s 10. A race car travelling at +44m/s is uniformly accelerated to a velocity of +22m/s over an 11s interval. What is its displacement during this time? +3.6x10 2 m 11. A rocket travelling at +88m/s is accelerated to +132m/s over a 15s interval. What is its displacement during this time? +1.7x10 3 m 12. A car accelerates at a constant rate from 15m/s to 25m/s while it travels 125m. How long (in seconds) does this motion take? 6.3s

2 13. A bike rider accelerates to a velocity of 7.5m/s during 4.5s. The bikes displacement is +19m. What was the initial velocity of the bike?.94m/s 14. An airplane starts from rest and accelerates at a constant +3.00m/s 2 acceleration for 30.0s before leaving the ground. What is the displacement during this time? 1.35x10 3 m 15. Starting from rest, a race car moves 110m in the first 5.0s of uniform acceleration. What is the car s acceleration? 8.8m/s An object accelerates uniformly from rest to a velocity of 12.0m/s west in 3.40s. Calculate the acceleration of the object? (3.53m/s 2 west) 17. An object accelerates uniformly from rest. If the final velocity of the object after 4.7s is 15m/s east, what is the displacement? (35m east) 18. An object accelerates uniformly from rest at a rate of 1.9m/s 2 right for 5.0s. Find a) The displacement (24m right) b) the final velocity (9.5m/s right) c) the distance traveled (24m) d) the final speed (9.5m/s) 19. An object initially traveling at a velocity of 2.0m/s west accelerates uniformly at a rate of 1.3m/s 2 west. During this time of acceleration, the displacement of the object is 15m. Find a) the final velocity (6.6m/s west) b) the final speed (6.6m/s) 20. An object accelerates uniformly from a velocity of 5.0m/s north at a rate of 3.0m/s 2 north, what is the velocity of the object at 2.9s? (14m/s) 21. An object accelerates, uniformly from rest. If it travels 26.0m south, and reaches a velocity of 11.0m/s south, how long was the object accelerating? (4.73s) 22. An object accelerates uniformly from rest at a rate of 2.40m/s 2 west. How long (time) was the object traveling when a velocity of 12.0m/s west was reached? (5.00s) 23. While accelerating uniformly from rest, an object is displaced 19.0m north in 7.10s. What is the velocity at this time? (5.35m/s north) 24. An object travels 8.0m south in 3.2s while uniformly accelerating at a rate of 0.71m/s 2 south. What was the initial velocity of the object? (1.4m/s south) 25. An object uniformly accelerates from 15.0m/s west to 35.0m/s west. What is the rate of acceleration if the displacement during this time was 43.0m? (11.6m/s 2 west) 26. An object accelerates uniformly at a rate of 1.50m/s 2 east for 10.0s. If the velocity of the object reaches 25.0m/s east at this time, what was the initial velocity? (10.0m/s west) 27. An object was uniformly accelerated from rest at a rate of 3.10m/s 2 south. If this object reaches a velocity of 12.4m/s south in 4.00s, what is the displacement of the object while it is accelerating? (24.8m south) 28. An object initially at rest is uniformly accelerated to a velocity of 10.0m/s west in 2.50s. If during that time the displacement of the object was 12.5m west, what was the rate of acceleration? (4.00m/s 2 ) 29. An object was displaced 19.6m east while accelerating from rest. If the average velocity of the object was 5.00m/s east, what was the rate of acceleration? (2.55m/s 2 east) 30. An object uniformly accelerates at a rate of 1.00m/s 2 east. While accelerating at this rate, the object is displaced 417.2m east in a time of 27.0s. What velocity did the object reach in this time? (29.0m/s east)

3 Acceleration Whenever the velocity of an object is changing, we say that the object is accelerating. The meaning of average acceleration can be illustrated by considering a plane during takeoff. The figure below shows how the velocity of the plane changes as the plane moves down the runway. During an elapsed time interval t = t f t i, the velocity changes from an initial value of v i to a final value of v f, the change in velocity being v = v f - v i. Therefore the average acceleration is a = v f v i / t = v / t Example Suppose the plane in the picture below starts from rest (v i = 0) when t i = 0. The plane accelerates down the runway and at t = 29s attains a velocity of v = +260km/h, where the plus sign indicates the velocity points to the right. Determine the average acceleration of the plane.

4 Solution: a = v f v i / t = 260km/h 0km/h / 29s = +9.0km/h/s The average acceleration of the plane is nine kilometers per hour per second. This means that the velocity of the plane changes by 9km/h every second. Other Acceleration Formulas d = v i t + ½ at 2 d = v f t - ½ at 2 v f 2 = v i 2 + 2ad

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