1. Devil physics The baddest class on campus Pre-DP Physics

2. Giancoli Chapter 2: Describing motion: kinematics in one dimension
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.

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

4. 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

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

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 Galilei ( )
Sir Isaac Newton ( )
Building blocks of all areas of modern physics

8. Mechanics Two major divisions: Chapters 2 and 3 deal with kinematics
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: 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: mi
Displacement
Pikes Peak
14,110 ft
7,610 ft
1.44 mi
Manitou Springs
6,500 ft θ

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

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 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 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 Diplacement divided by time elapsed
Avg. velocity = displacement/time elapsed

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

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

33. 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

34. 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

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

36. Questions?

37. Homework
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