Reading Quiz(2) Review

1. Reading Quiz(2)Review A rock is falling with uniform acceleration. Which of the following statements is FALSE? graph of its position versus time is a straight line graph of its speed versus time is a straight line graph of its acceleration versus time is a straight line

2. Question 1: Consider various types of weather maps and navigational maps of the North Atlantic, that plot out temperatures, storm conditions, etc. Which of the following quantities might best be represented as vectors on the map? Air temperature Water temperature Ocean currents Barometric pressure None of the above

3. Figure 2.5The direction of the velocity changes as the car moves around the curve, so that the velocity v2 is not the same as the velocity v1 even though the speed has not changed.

4. Figure 2.6The direction of the velocity changes whena ball bounces from a wall. The wall exerts a force on the ball in order to produce this change.

5. Acceleration Acceleration is the change in the velocity of an object during a certain time interval. [If a car is moving in the positive direction] A car that speeds up has a positive acceleration. A car that slows down has a negative acceleration. Acceleration = {final velocity - initial velocity}/time Because Acceleration is a vector; a negative acceleration can mean that the car is speeding up in the negative direction!

6. Summary of Chapter 2: Speed is distance divided by time. “Average” speed is over a longer time interval; “instantaneous” is over the shortest possible time. Velocity is a vector which denotes both the size of the speed, as well as its direction. Acceleration is how much the velocity changes during a specified time interval:

7. Question 2: Consider what happens when the far end of the track is lifted up. The ball will move up, then roll back down. Which of these is true: First the acceleration is positive, then it is negative. The acceleration is constant. The velocity is constant. The speed is constant, but the velocity changes. None of the above.

8. B x A C t D Question 3: Which position corresponds to a particle at rest? A. B. C. D.

9. B x A C t D Question 4: Which position corresponds to a particle changing directions? A. B. C. D.

10. B x A C t D Question 5: Which position corresponds to the particle having its greatest speed? A. B. C. D.

11. x x x x x t t t t t 1. 2. Question 6: Which plot describes a particle that is NOT in motion? • 1 • 2 • 3 • 4 • 5 3. 4. 5.

12. x x x x x t t t t t 1. 2. Question 7: Which plots describe a particle with a positive velocity? • 1 • 1 and 3 • 1 and 2 and 4 • 2 and 3 • 2 and 3 and 5 3. 4. 5.

13. Question 8: Consider what happens when the far end of the track is raised. The ball will move up the track, then roll back down. Which of these is true: First the acceleration is positive, then it is negative. First the velocity is positive, then it is negative. Both #1 and #2. None of the above.

14. Question 9: You are riding on a Ferris wheel at an amusement park, making one revolution every 30 seconds. Choose the TRUE statement: Your acceleration is greatest at the top. Your acceleration is greatest at the bottom. The size of your acceleration never changes. The direction of your acceleration never changes. You have no acceleration.

15. Summary of Ch 2, continued: 4. Motion can be graphed. The slope of distance vs. time is instantaneous speed. The slope of velocity vs. time is acceleration. 5. Uniform acceleration means a = constant. This leads to two “simple” equations:

16. Figure 2.17The acceleration graph for uniform acceleration is a horizontal line. The acceleration does not change with time.

17. Figure 2.18Velocity plotted against time for uniform acceleration, starting from rest. The average velocity is equal toone-half the final velocity.

18. Figure 3.7Velocity and distance values for the dropped ball shown at half-second time intervals.

19. Figure 3.8A plot of distance versus time for the dropped ball.

20. Figure 3.10The velocity vectors at different points in the flight of a ball thrown upward with a starting velocity of +20 m/s.

21. Figure 3.11A plot of the velocity versus time for a ball thrown upward with an initial velocity of +20 m/s. The negative values of velocity represent downward motion.

22. Figure 3.13The horizontal and vertical motions combine to produce the trajectory of the projected ball.

23. Summary of Ch 2, continued: 4. Motion can be graphed. The slope of distance vs. time is instantaneous speed. The slope of velocity vs. time is acceleration. 5. Uniform acceleration means a = constant. This leads to two simple equations: