2. 1 1- D Motion Kinematics “Motion in a Straight Line!”

3. 2 KINEMATICS - the process of motion is integral to the description of matter characteristics! - all matter is moving - therefore a method must be formulated for accuracy!

4. 3 Describe motion in a straight line Which car has the greatest velocity?BLUE Which car has a constant velocity?RED Which 2 cars have the same average velocity? RED and GREEN

5. 4 DISTANCE vs. DISPLACEMENT 1. DISTANCE - defined as the magnitude or length of motion - NO DIRECTION INDICATED symbol = d 2. DISPLACEMENT - magnitude and direction of motion symbol = s

6. 5 Speed Speed: The “rate” of change of distance covered. A rate is anything compared to time. In own words, how “fast”. distance Speed = ----------------- time Typical units: mi/hr, km/hr, m/s...

7. 6 Average Speed Total distance covered Average speed = -------------------------- total time SPEED d t

8. 7 Instantaneous Speed: The speed of an object at any particular instant. The average speed and instantaneous speed may not be the same! A car that gradually speeds up more and more has an instantaneous speed that always changes..

9. 8 Constant Speed An object could be moving at a steady rate. Thus, its average and instantaneous speed would be the same! GBS Physics - speed vs. velocity

10. 9 SOME EXAMPLES 1. A motocross rider travels a total distance of 300 km during a race. It takes the rider 2.5 hours to travel this distance. What is the average speed of the rider? SOLUTION: AVE SPEED = Total Distance / time speed = 300 km / 2.5 hrs = 120 km/hr v d t

11. 10 SOME EXAMPLES speed = 454 km / 7200s = 454000m / 7200s = 63 m/s v d t A high speed train travels 454 km in 7200 seconds. What is the train’s average speed? Formula : v (speed) = d/t d t

12. 11 Velocity Velocity and speed are often used interchangeably. They are not the same term though! Speed is a scalar quantity. It has a number value only. No direction. Velocity is a vector quantity. It has a size and direction.

13. 12 Question: A car is traveling at a constant 60mi/hr in a circular path. Does it have a constant speed? Does it have a constant velocity?

14. 13 Acceleration Acceleration: The rate of change in speed and/or direction (or velocity) How fast something speeds up, slows down, or turns.

15. 14 If an object has a constant velocity, then its acceleration would be zero. If an object is slowing down, it is decelerating:

16. 15 change in velocity acceleration = ------------------------ time interval Δv a = ----------- Δt Δ, Greek letter delta = change in GBS Physics - Acceleration

17. 16 Change in Speed/Velocity Acceleration = -------------------------- total time Acc vv t Eq: a = ∆v or a = v f – v i ∆t t f - t i Units m, km, mi, ft, s 2 h. s h. s s 2 Always a distance unit divided by two units of time. Why?

18. 17 Ex: A particular car goes from rest to 90km/hr in 10 sec, what is its acceleration? Δv = 90 km/hr Δt = 10 sec a = Δv/ Δt = 90 km/hr/10 sec =9 km/hr / sec notice units... This means its velocity is changing by 9km/hr every second it accelerates at that rate.

19. 18 Velocity vs. Acceleration? If you are flying at a constant 500 mi/hr on a jet airplane, do you have a large velocity? A large acceleration?

20. 19 2. The stealth fighter accelerates from 700 mph to 1200 mph in 10 seconds. What is the acceleration of the aircraft? Acceleration = change in velocity / time ( 1200 mph - 700 mph) / 10 s 50 mph/s ( 500 mph) / 10 s = Acc vv t

21. 20 3. A toy car accelerates from rest to a speed of 100 m/s in 5 seconds. What is the acceleration? Acceleration = change in velocity / time (100 m/s - 0 m/s) / 5 s 20 m/s/s or 20 m/s 2

22. 40m-20m 4 s-2 s = 20m / 2s = 10 m/s

23. 22 GRAPHICAL REPRESENTATION OF VELOCITY slope - the slope of a displacement vs. time curve would be the velocity Time is always the independent or x-axis. Plot points and draw a line of best fit. Remember! Label axis with units, and title graph. DO NOT CONNECT DOTS! GBS Physics - position vs. time

24. 23 Data Chart : Constant Velocity Elapsed time (seconds)Distance (meters) 00 24 48 612 816 1020 1224 Copy the data chart and construct a Distance vs. Time Graph Answer on the next SLIDE

25. 24 Graph: Constant Velocity

26. 25

27. 26 Data Chart Constant Acceleration! What type of motion? Elapsed time (seconds) Distance (meters) 0.00 4.08 8.032 12.072 16.0128 20.0200 24.0288

28. 27 Graph of Data: Constant Acceleration

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30. 29 Constant Velocity Positive Velocity Changing Velocity (acceleration)

31. 30 Fast, Rightward (+) Constant Velocity http://www.physicsclassroom.com/mmedia/kinema/cpv.html Fast, Leftward (-) Constant Velocity

32. 31 GRAPHICAL REPRESENTATION OF ACCELERATION slope - the slope of a velocity vs. time curve would be the acceleration GBS Physics - velocity vs time

33. 32 Velocity Time Graph Elapsed time (seconds) Distance (meters) Velocity (m/s) 00.0 24.02.0 48.02.0 612.02.0 816.02.0 1020.02.0 1224.02.0 Copy the data chart and construct a VELOCITY vs. TIME Graph

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35. 34 Uniform Acceleration : Velocity vs. Time Elapsed time (seconds) Distance (meters) 0.00 4.08 8.032 12.072 16.0128 20.0200 24.0288

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37. 36 Positive Velocity Positive Acceleration Positive Velocity Zero Acceleration

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