# QQ 1 A car moves along a test

• Slides: 21

QQ

1. A car moves along a test track in the + x -direction. The velocity versus time graph below records this, with line segments L through P identifying different stages of motion. Rank the magnitudes Of acceleration of the stages of motion of the car from greatest to least. N > P > L >

2. Jesse fires a bullet from a rifle with at velocity of 330 m/s into a dense material that stops the bullet in a distance of 30 cm. What is the bullet’s acceleration? -182, 000 m/s 2

3. A vehicle undergoes acceleration when it a. gains speed. b. decreases speed. c. changes direction. d. all of the above

4. Speed and acceleration are actually a. one and the same concept, but expressed differently. b. rates of one another. c. entirely different concepts. d. expressions of distance traveled.

5. The slope of a speed-versustime graph represents: a. distance traveled. b. velocity. c. acceleration. d. air resistance.

6. Two rocks with masses of 5 kg and 10 kg are dropped from a height of 20 m above the ground. Which one has the greatest velocity when it reaches the ground? They accelerate at the same rate and have the same velocity when they hit.

7. A rock falls 180 m from a cliff into the ocean. How long is it in free fall? a. 6 s b. 10 s c. 18 s d. 180 s

8. Sharon drops her wallet from the top floor of a tall building. It takes 2. 8 seconds for the wallet to reach the ground. What was the wallet’s speed just before hitting the ground? V = 27. 44 m/s

9. Calculate the instantaneous velocity at t = 35. 10 30 . 33 m/s

10. Olympic gold medalist Michael Johnson runs one time around the track - 400 meters - in 38 seconds. What is his average velocity? Since average velocity is displacement over time, his average velocity is also 0 m/s.

11. A fullback is running down the football field in a straight line. He starts at the 0 -yard line at 0 seconds. At 1 second, he is on the 10 -yard line; at 2 seconds, he is on the 20 -yard line; at 3 seconds, he is on the 30 -yard line; and at 4 seconds, he is on the 40 -yard line. This is evidence that A) B) he is accelerating he is covering a greater distance in each consecutive second. C) he is moving with a constant speed (on average)

12. Ryan through his hat straight up with an initial speed of 15 m/s. What is the maximum height the hat reached before it began to fall back down? 11. 5 m

13. Sharon drops her wallet from the top floor of a tall building. It takes 2. 8 seconds for the wallet to reach the ground. Its final velocity was -27. 4 m/s. What was the height of the building? 38. 4 m

14. Olympic gold medalist Michael Johnson runs one time around the track - 400 meters - in 38 seconds. What is his displacement? Michael finishes where he started, so he is not "out of place. " His displacement is 0 meters.

15. As an object freely falls, its ____. b. acceleration a. speed increases c. both of these d. none of these As an object falls, it accelerates; this means that the speed will be changing. While falling, the speed increases by 10 m/s every second. The acceleration is a constant value of 10 m/s/s; thus, choice b should not be chosen

16. Which of the following statements about vectors and scalars are TRUE? 1 -Vectors are large quantities & scalars are small quantity. 2 -Scalars have magnitude and vectors do not. 3 - Vectors are described with a direction and scalars are not. 4 -A scalar quantity depends only upon the initial and final values of the quantity; this is not the case for vector quantities. 5 -The quantity 20 m/s, north is a speed and as such is a scalar quantity. 6 -The quantity 9. 8 m/s/s is an acceleration value and as such is a vector quantity.

17. If car A passes car B, then car A must be ____. A) accelerating. B) accelerating at a greater rate than car B. C) moving faster than car B and accelerating more than car B. D) moving faster than car B, but not necessarily accelerating.

18. Which one of the following is NOT consistent with a car which is accelerating? a) A car is moving with an increasing speed. b) A car is moving with a decreasing speed. c)A car is moving with a high speed. d) A car is changing direction

19. Which one of the following statements is NOT true of a freefalling object? An object in a state of free fall ____. a) falls with a constant speed of -10 m/s. b) falls with a acceleration of -10 m/s/s. c) falls under the sole influence of gravity. d) falls with downward acceleration which has a constant magnitude

20. What is the acceleration of a car that maintains a constant . velocity of 55 mi/hr for 10. 0 seconds? If the velocity is constant, there Is no acceleration. A = 0