1 / 25

Motion

Motion. Chapter 2. How can we describe motion? Words Pictures/Diagrams Which is better? Why?. Describing Motion. Motion diagrams --- a series of images showing the positions of a moving object at equal time intervals

dee
Download Presentation

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. Motion Chapter 2

  2. How can we describe motion? • Words • Pictures/Diagrams • Which is better? Why? Describing Motion

  3. Motion diagrams--- a series of images showing the positions of a moving object at equal time intervals • Particle Motion--- a simplified version of a motion diagram in which the object is replaced by a series of single points -size of the object must be much less than the distance it moves Motion Diagrams

  4. Motion Diagrams

  5. Vectors Scalars numbers without direction Distance Time Temperature Examples: distance and time • represented by arrows (shows direction) • size (magnitude) • direction • Examples: velocity and acceleration Quantities in Physics

  6. -An important part of describing the motion of an object is to describe how far it has moved, which is distance. Distance how far it has moved • -The SI unit of length or distance is the meter (m). Longer distances are measured in kilometers (km).

  7. -Suppose a runner jogs to the 50-m mark and then turns around and runs • back to the 20-m mark. Displacement • The runner travels 50 m in the original direction (north) plus 30 m in the opposite direction (south), so the total distance she ran is 80 m.

  8. -Displacement is the distance and direction of an object's change in position from the starting point. Displacement • -The runner’s displacement is 20 meters north of the starting point.

  9. Plotting a Distance-Time Graph -If we plot a distance-time graph, we can see the relationship between speed, distance and time -Time is on the x-axis and distance is on the y-axis

  10. Speed and velocity Chapter 2

  11. -You also might want to describe how fast it is moving. Speed • : the distance an object travels per unit of time. • -Speed is a scalar

  12. -A speedometer shows how fast a car is going at one point in time or at one instant. • -The speed shown on a speedometer is the instantaneous speed. • -Instantaneous speed is the speed at a given point in time. Instantaneous Speed

  13. -Speed describes only how fast something is moving. • -To determine direction you need to know the velocity. Velocity • :the speed of an object and • the direction of its motion. • -Velocity is a vector

  14. -Because velocity depends on direction as well as speed, the velocity of an object can change even if the speed of the object remains constant. Velocity • -The speed of this car • might be constant, but its • velocity is not constant • because the direction of motion is always changing.

  15. the rate of change of displacement with time • has magnitude AND direction • change in distance (the displacement) divided by the change in time (the time interval) v = (df-di)/(tf-ti) Average Velocity

  16. Given Unknown Equation Substitute Solution GUESS method

  17. Whatis the velocity of a truck that travels 10. km in 10. minutes? • ANS: 17 m/s Problems

  18. What is the average velocity of a commercial jet that travels from New York to Los Angeles (4800 km) in 6.00 hours? (convert answer to m/s) • ANS: 220 m/s Problems

  19. A car is traveling at an average velocity of 70.0 m/s. How many km would the car travel in 6.5 hours? • ANS: 1700 km Problems

  20. If you run 100. m at a speed of 5.0 m/s and then walk 100. m at 1.0 m/s what is your average velocity? • ANS: 1.7 m/s Problems

  21. A rabbit and a turtle are practicing for their big race. The rabbit covers a 30. m practice course in 5.0 seconds, the turtle covers the same distance in 120 seconds. If the actual race is run on a 96 m course, by how many seconds will the rabbit beat the turtle? • ANS: 370 sec Problems

  22. We can use the velocity to determine an object’s position! • An object’s position is equal to the average velocity multiplied by time plus the initial position. Symbol = dt Units = m dt = v ∙ t + di Average Velocity – Object’s Position

  23. What distance is traveled by a police car that moves at a constant velocity of 1.5 km/minute for 5.0 minutes? • ANS: 7.5 km Problems

  24. What distance would be covered in 10.0 minutes by a train that travels at a constant speed of 500. meters every 10.0 seconds? • ANS: 3.00 x 104 m Problems

  25. A tsunami caused by an earthquake occurring in Alaska in 1946 consisted of several huge waves which were found to travel at the average speed of 790 km/hr. The first of the waves reached Hawaii 4 hours 34 minutes after the earthquake occurred. From this data, calculate how far the origin of the tsunami was from Hawaii? • ANS: 4,000,000 m Problems

More Related