-Speed and Velocity -Uniform Linear Motion

1. -Speed and Velocity-Uniform Linear Motion Physics Mrs. Coyle http://www.wallpaperbase.com/wallpapers/sports/formula1/formula_1_3.jpg

2. Speed and Velocity • Average Speed= Total Distance Travelled Time v=d/t (Scalar) • Average Velocity= Displacement Time v= Dd / D t =(d2-d1) / (t2- t1)(Vector)

3. Vectors and Scalars • Scalar  Magnitude (size) • Vectors  Magnitude and Direction

4. Example: • A car is travelling at an average velocity of 55km/h, N, when the driver sees a box on the road. If the reaction time of the driver is 0.45sec, how far does the car travel at that velocity before the driver even begins to break?

5. Instantaneous SpeedInstantaneous Velocity • Instantaneous Speed • Speed at a given instant (ex: speedometer of car) • Instantaneous Velocity • Velocity at a given instant • Instantaneous speed is the magnitude of instantaneous velocity.

6. Note: Average speed is equal to the magnitude of average velocity ONLY when velocity is CONSTANT (magnitude and direction).

7. Uniform Linear Motion: • Motion with constant velocity • Straight line • Same direction

8. If the speed on this ride is constant, is the motion uniform linear motion?

9. Graphs of Motion: -Position-Time -Velocity-Time -Acceleration-Time

10. Example: Position vs Time for Uniform Linear Motion Position (m) o Time (s) Note: The slope of the line in a Position-Time Graph equals the average velocity.

11. Example: Velocity vs Time for UniformLinear Motion Velocity (m/s) o Time (s)

12. Example: Position vs Time Graph Position, (m) • What is the avge velocity at the time intervals: • (0s-1s) (1s-1.5s) (1.5s-1.7s) (1.7s-2.0s) • Draw the velocity – time diagram. 20.0 10.0 A o 0.5 1.0 1.5 2.0 Time, (s)

13. Note: • The area under the line (curve) of a velocity-time graph is equal to the displacement of the object during that time interval.