Devil physics The baddest class on campus Pre-DP Physics

1. Devil physicsThe baddest class on campusPre-DP Physics

2. SC.912.P.12.2: Analyze the motion of an object in terms of its position, velocity, and acceleration (with respect to a frame of reference) as functions of time. Giancoli Chapter 2: Describing motion: kinematics in one dimension

3. 2-1: Reference Frames and Displacement 2-2: Average Velocity 2-3: Instantaneous Velocity Giancoli Chapter 2: Describing motion: kinematics in one dimension

4. Objectives • Know the meaning of the terms mechanics, kinematics and dynamics • Know the difference between distance and displacement and how to measure each • Know the difference between average speed and average velocity • Understand the concept of instantaneous velocity

5. Objectives • Calculate average speed for a given distance and time • Calculate average velocity for a given displacement and time

6. Introductory Video: Displacement, Velocity and Acceleration

7. Mechanics • The study of the motion of objects and the related concepts of force and energy. • Galileo Galilee (1564-1642) • Sir Isaac Newton (1642-1727) • Building blocks of all areas of modern physics

8. Mechanics • Two major divisions: • Kinematics: description of how things move • Dynamics: force and why things move the way they do • Chapters 2 and 3 deal with kinematics

9. Translational Motion • Objects that move without rotating • Moves along a straight-line path • One-dimensional motion

10. Translational Motion

11. Translational Motion

12. Frame of Reference • The point from which you are viewing something • The point from which you are measuring something • We normally place a set of coordinate axes (a coordinate plane) with the origin resting on the reference point

13. Distance vs. Displacement • Distance: measurement of the entire length travelled without respect to direction • Displacement: change in position of an object, or, how far the object is from its original position and in what direction • Includes both magnitude and direction

14. Distance vs. Displacement • Pike’s Peak Marathon Pikes Peak 14,110 ft 7,610 ft 1.44 mi Manitou Springs 6,500 ft

15. Distance vs. Displacement • Pike’s Peak Marathon Distance: 14.1 mi Pikes Peak 14,110 ft 7,610 ft 1.44 mi Manitou Springs 6,500 ft

16. Distance vs. Displacement • Pike’s Peak Marathon Distance: 14.1 mi Displacement Pikes Peak 14,110 ft 7,610 ft 1.44 mi θ Manitou Springs 6,500 ft

17. Scalar vs. Vector Distance: 14.1 mi Displacement Pikes Peak 14,110 ft 7,610 ft 1.44 mi θ Manitou Springs 6,500 ft

18. Displacement • “The change in position is equal to the second position minus the first position” • Example: You are standing on a number line at 23 and suffer a blow to the head. When you wake up, you are laying at -17. What was your displacement?

19. Displacement • Example: You are standing on a number line at 23 and suffer a blow to the head. When you wake up, you are laying at -17. What was your displacement? • Your displacement is 40 to the left

20. Speed • Distance traveled in a given time interval • Distance per unit time • 60 mph, 35 m/s • Vector or scalar?

21. Average Speed • Distance travelled divided by time elapsed • Avg. speed = distance travelled/time elapsed

22. Average Velocity • Displacement divided by time elapsed • Avg. velocity = displacement/time elapsed

23. Speed vs. Velocity Distance: 14.1 mi Displacement Pikes Peak 14,110 ft 7,610 ft 1.44 mi θ Manitou Springs 6,500 ft

24. Speed vs. Velocity • Can the magnitude of the velocity ever be more than speed for any given timed movement of a body?

25. Speed vs. Velocity • Can the magnitude of the velocity ever be more than speed for any given timed movement of a body? Distance equals displacement Distance is greater than or equal to displacement but never less than displacement

26. Speed vs. Velocity • Can the magnitude of the velocity ever be more than speed for any given timed movement of a body? • Since distance is always greater than or equal to displacement • And since speed is distance/time • And since velocity is displacement/time • Speed will always be greater than or equal to velocity

27. Avg. Velocity: The Equation

28. Average Velocity of a Car

29. Average Velocity – Air Track

30. Instantaneous Velocity • Velocity at a split second of time • The average velocity of an infinitesimally short time interval

31. Instantaneous Velocity: The Equation

32. Instantaneous Velocity – Air Track

33. Instantaneous Velocity • Instantaneous speed will always equal the magnitude of the instantaneous velocity. Why?

34. Instantaneous Velocity • Instantaneous speed will always equal the magnitude of the instantaneous velocity. Why? • When distance/displacement become infinitesimally small, their difference also becomes infinitesimally small, approaching zero

35. Objectives • Know the meaning of the terms mechanics, kinematics and dynamics • Know the difference between distance and displacement and how to measure each • Calculate average speed for a given distance and time • Calculate average velocity for a given displacement and time

36. Objectives • Know the difference between average speed and average velocity • Understand the concept of instantaneous velocity

37. Questions?

38. Homework • #1-11