1 / 33

Describing Motion

Describing Motion. Chapter 2. Motion. Motion is an object’s change in position. Motion. It is usually measured with respect to a reference point. A reference point is a stationary object, like a building or a street sign. Questions to Ponder….

matt
Download Presentation

Describing Motion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Describing Motion Chapter 2

  2. Motion • Motion is an object’s change in position.

  3. Motion • It is usually measured with respect to a reference point. • A reference point is a stationary object, like a building or a street sign.

  4. Questions to Ponder… • Can you think of a situation where you are in motion but yet do not know you are moving? • If this is possible, why is this so?

  5. Questions to Ponder… • Have you ever been tricked into thinking you were in motion but you were still at rest? • How is this possible?

  6. Distance • Distance is a measure of how far an object moves relative to a reference point.

  7. Distance • For example – A student walks 2.0 miles to school, then turns around and walks back home. • What is the total distance traveled?

  8. Distance • The total distance traveled by the student is 4 miles. • Distance does not involve a direction.

  9. Displacement • It involves both a magnitude ( a number)and a direction.

  10. Displacement • The distance and direction of an object’s change in position from the starting point.

  11. Displacement • For example – A student walks 2.0 miles east, stops, then turns around and walks 1.0 miles west.

  12. The displacement is • 2 miles east – • 1 mile west • = 1.0 mile east.

  13. Distance and Displacement In the following example, identify the distance and displacement. A physics teacher walks 4 meters East, 2 meters South, 4 meters West, and finally 2 meters North.

  14. Sample Problem • What is the skiers distance? Displacement? • The skier moves from A to B to C to D.

  15. The skier covers a distance of (180 m + 140 m + 100 m) = 420 m Displacement is 140 m, rightward.

  16. Your Turn !!!! • Try to solve this word problem. • Draw a picture to help visualize what is happening.

  17. Distance vs. Displacement Example • Abby drives 45 miles west, stops to eat, then drives an additional 35 miles west when she realizes she left her purse at the restaurant. She turns around and drives back 35 miles east to the restaurant. • How far did Abby drive? • What is Abby’s displacement?

  18. Distance vs. Displacement Example • Answer: • How far did Abby drive? 115 miles • What is Abby’s displacement? 45 miles west

  19. Speed • Miles/hour • Kilometers/hour • Meters/second

  20. Speed • Speed is how fast an object is moving. • It is a measure of distance traveled during a period of time.

  21. Speed • It is a rate – a number of something per time • Ex. Pulse Rate- number of heart beats/minute

  22. Speed • Formula and Units • Speed = distance (meters or kilometers) time (seconds or hours)

  23. Speed • Distance/ time • Calculate the speed of the rabbit and turtle for a 5 mile race. • Rabbit- 1 hour • Turtle- 10 hours

  24. Speed • Turtle: .5 mph ( 5 miles/ 10 hours) • Rabbit: 5mph ( 5miles / 1 hour )

  25. ***Speed doesn’t involve direction***

  26. Constant Speed • Car on highway, put it in cruise control • Car neither slows or speeds up • Your speed is constant

  27. Changing Speed • Usually speed isn’t constant • Ex. Riding a bike • P. 41

  28. Average speed vs. Instantaneous Speed

  29. Instantaneous Speed speed at a specific instant speed shown on a speedometer Average speed total distance covered in a particular time v = d/t Speed Continued…

  30. Velocity • Hurricane Gustavo at 20 km/hr is east of your city. Should you be worried?

  31. Velocity • Gives both speed and direction! • 20 km/hr westward direction

  32. Velocity It is a rate – change in displacement during a certain time period. • Formula and Units • Velocity = displacement (meters or kilometers) time (seconds or hours) ** don’t forget direction… north, south, east, west, up, down, right, left

  33. Instantaneous velocity the velocity at a specific instant initial velocity and final velocity Average Velocity the final displacement of an object during a certain time period v = d/t Velocity Continued…

More Related