1. Physical Science
Chapter 11:
Motion

2. How Important is Motion? How Do You Interpret Motion?

3. Motion All Kinds of Motion Perceiving motion is instinctive
Your eyes pay more attention to moving objects than to stationary ones
Movement is all around you
Movement travels in many directions
straight-lines
curved paths
spirals
swirls

4. All Kinds of Motion Motion Frame of Reference How Motion is Perceived
Relative Motion
Moving Objects with Respect to One Another

5. Motion Picturing Motion Particle Model Constant Velocity
Increasing Velocity
Decreasing Velocity

6. Motion Coordinate System
A coordinate system tells you the location of the zero point of the variable you are studying and the direction in which the values of the variable increase

7. Motion Coordinate System For Movement Along a Straight Line
Coordinates Would Also be in a Straight Line
ex. Number Line

8. Motion Coordinate System X – Y Coordinate Provides Origin
The origin is the point at which both variables have the value zero
Time and Position
Position in Different Axis

9. Motion Coordinate System Origin
The arrow shown in the figure represents the runner’s position, which is the separation between an object and the origin

10. Motion Coordinate System
The length of the arrow shows how far an object is from the origin and indicates its distance from the origin
A position 5m left of the origin, would be a negative position

11. Motion
Time Interval (Dt)
Time Elapsed During Motion

12. Motion Displacement (d)
The change in position during the time interval between ti and tf is called displacement

13. Motion Displacement (Dd)
Displacement is equal to the final position minus the initial position

14. Motion Distance Displacement Length of the Path Between Two Points
Scalar Quantity
Displacement
Length Between the Start Point and the End Point
Vector Quantity

15. Motion
Distance vs. Displacement

16. Scalar and Vector Quantities
Motion
Scalar and Vector Quantities
Scalar Quantity
Magnitude (number and units)
ex. 15km or 250C
Vector Quantity
Magnitude and Direction
ex. 15km north or 9.8m/s2 down

17. Vectors Motion Represented by Arrows
Direction of the Arrow Represents the Direction of the Vector
The Length of the Arrow is Proportional to the Magnitude of the Vector

18. Problem Motion Which of the following are vectors? Temperature
Distance
Displacement

19. Solution Motion Which of the following are vectors?
Temperature (scalar)
Distance (scalar)
Displacement (vector)

20. Motion
Resultant
The vector that represents the sum of the other vectors is called the resultant
The resultant always points from the tail of the first vector to the tip of the last vector

21. Movement Along a Straight Line
Motion
Movement Along a Straight Line
Motion relates to position and time.
In the figure below, the car has moved from point A to point B in a specific time period.

22. Motion Picturing Motion 100m Dash

23. Motion
What Is Speed?
What Is Velocity?

24. Motion
Average Speed
The absolute value of the slope of a position-time graph
The sign of the slope tells you in what direction the object is moving
Scalar Quantity

25. Average Velocity Motion
The slope tells you in what direction the object is moving
Vector Quantity

26. Average Velocity Motion Units Displacement – Unit of Distance Time
Meter (m)
Time
Second (s)
Velocity
m/s

27. Motion Average Velocity Using Displacement and Time
d = change in displacement
Average of Two Velocities

28. Motion
Average Velocity
Calculated Over a Period of Time

29. Position – Time Graphs Motion
Information about an object’s position at various times
Helpful in determining the displacement of an object during various time intervals

30. Motion
Position – Time Graphs

31. Motion
Position – Time Graphs

32. Motion Equivalent Representations
All Contain the Same Information about an Object’s Motion

33. Motion Combining Velocities Velocity is a Vector Vectors can be Added
Magnitude and Direction
Vectors can be Added

34. What Do You Think of When You Think of Acceleration?
Motion
What Is Acceleration?
What Do You Think of When You Think of Acceleration?
What is it to Accelerate?

35. Motion Acceleration Gives You the “Feeling” of Being Pushed
Change in Velocity over a Period of Time
Compare
0 Velocity
Constant Velocity
Increasing Velocity
Decreasing Velocity

36. Motion
Acceleration
The Slope of a Velocity – Time Graph

37. Motion
Acceleration
Change in Velocity over a Period of Time

38. Motion Acceleration Units Velocity = m/s Time = Second
Acceleration = m/s/s or m/s2

39. Motion Negative Acceleration Acceleration can be Positive or Negative
There is No Such Thing as Deceleration
Negative acceleration means slowing down

40. Motion
Graphing Acceleration

41. Motion
Graphing Acceleration

42. Motion
Graphing Acceleration

43. Motion Free Fall Acceleration Due to Gravity ONLY!
Galileo concluded that, neglecting the effect of the air, all objects in free fall had the same acceleration. It didn’t matter what they were made of, how much they weighed, what height they were dropped from, or whether they were dropped or thrown.

44. Motion
Free Fall
The acceleration of falling objects, given a special symbol, g, is equal to 9.80 m/s2.
The acceleration due to gravity is the acceleration of an object in free fall that results from the influence of Earth’s gravity only.

45. Motion
Free Fall

46. Motion
Free Fall
At the top of the flight, the ball’s velocity is 0m/s. What would happen if its acceleration were also zero? Then, the ball’s velocity would not be changing and would remain at 0 m/s.

47. Motion
Free Fall
If this were the case, the ball would not gain any downward velocity and would simply hover in the air at the top of its flight.

48. Motion
Free Fall
Because this is not the way objects tossed in the air behave on Earth, you know that the acceleration of an object at the top of its flight must not be zero. Further, because you know that the object will fall from that height, you know that the acceleration must be downward.

49. Motion
Free Fall
Amusement parks use the concept of free fall to design rides that give the riders the sensation of free fall.
These types of rides usually consist of three parts: the ride to the top, momentary suspension, and the plunge downward.
When the cars are in free fall, the most massive rider and the least massive rider will have the same acceleration

50. Motion
Homework