1. Chapter 5 Preview Section 1 Measuring Motion
Matter in Motion
Preview
Section 1 Measuring Motion
Section 2 What Is a Force?
Section 3 Friction: A Force That Opposes Motion
Section 4 Gravity: A Force of Attraction
Concept Mapping

2. Chapter 5
Section 1 Measuring Motion
Objectives
Describe the motion of an object by the position of the object in relation to a reference point.
Identify the two factors that determine speed.
Explain the difference between speed and velocity.
Analyze the relationship between velocity and acceleration.
Demonstrate that changes in motion can be measured and represented on a graph.

3. Chapter 5
Section 1 Measuring Motion
Standard
S8P3. Obtain, evaluate, and communicate information about cause and effect relationships between force, mass, and the motion of objects.
a. Analyze and interpret data to identify patterns in the relationships between speed and distance, and velocity and acceleration.

4. Chapter 5 We Observe Motion by Using a Reference Point
Section 1 Measuring Motion
We Observe Motion by Using a Reference Point
1. Motion is an object’s change in position relative to another object, or reference point.
2. The object that appears to stay in place is called a reference point.
3. The direction of an object’s motion can be described with a reference direction, such as north, south, east, west, up, or down.
Common Reference Points The Earth’s surface is a common reference point for determining motion.

5. Motion- click below to watch visual concept
You will complete #4
Relative Motion: Demonstration
Visual Concept

6. Speed Depends on Distance and Time
Chapter 5
Section 1 Measuring Motion
Speed Depends on Distance and Time
5. Speed is the distance traveled by an object divided by the time taken to travel that distance.
7. The SI unit for speed is meters per second (m/s). which we will use in science class. Or Kilometers per hour (km/h),
Americans use feet per second (ft/s), and miles per hour (m/h) when calculating speed in a car or bike.

7. Chapter 5 = Speed Depends on Distance and Time, continued
Section 1 Measuring Motion
Speed Depends on Distance and Time, continued
Determining Average Speed Average speed equals the total distance divided by the total time.
average speed =
total distance
total time
Recognizing Speed on a Graph Speed can be shown on a graph of distance versus time, as shown on the next slide.

8. Chapter 5
Section 1 Measuring Motion

9. Chapter 5
Section 1 Measuring Motion
Speed Comparison

10. Velocity: Direction Matters
Chapter 5
Section 1 Measuring Motion
Velocity: Direction Matters
8. The speed of an object in a particular direction is called velocity.
Speed and velocity are two different terms with two different meanings. Velocity must include a reference direction.

11. Velocity: Direction Matters, continued
Chapter 5
Section 1 Measuring Motion
Velocity: Direction Matters, continued
Changing Velocity You can think of velocity as the rate of change of an object’s position. An object’s velocity is constant only if its speed and direction don’t change.
Combining Velocities You can combine different velocities to find the resultant velocity. The next slide shows how you can combine velocities to find the resultant velocity.

12. VELOCITY OR SPEED? 45 M/S 30 KM/ HR NORTH 100 METERS PER MINUTE
56 M/S WEST
72 CM/SEC EAST
225 KM/MIN

13. Chapter 5
Section 1 Measuring Motion
Acceleration
9. The rate at which velocity changes over time is called acceleration. An object accelerates if its speed, or direction, or both change.
9. = speeding up, slowing down or changing direction
An increase in velocity is commonly called positive acceleration. A decrease in velocity is commonly called negative acceleration, or deceleration.

14. Conventional terminology to describe all motion is one of the following:
Leg A -- Constant Velocity – speed and direction remain the same
Leg B -- Positive Acceleration – object is speeding up
Leg C -- Negative Acceleration or deceleration – object is slowing down

15. DID ACCELERATION OCCUR?
You are riding your bike at 9km/h. 10 minutes later your speed is 6 km/h.

16. DID ACCELERATION OCCUR?
You ride your bike around the block at a constant speed of 11km/h.

17. DID ACCELERATION OCCUR?
You ride your bike in a straight line at a constant speed of 10 km/h
____

18. Chapter 5
Section 1 Measuring Motion
Circular Motion: Continuous Acceleration An object traveling in a circular motion is always changing its direction. Therefore, its velocity is always changing, so it is accelerating.
The acceleration that occurs in circular motion is known as centripetal acceleration.

19. Acceleration, continued
Chapter 5
Section 1 Measuring Motion
Acceleration, continued
Calculating Average Acceleration You can find average acceleration by using the equation:
average acceleration
=
final velocity  starting velocity
time it takes to change velocity
Velocity is expressed in meters per second (m/s), and time is expressed in seconds (s). So acceleration is expressed in meters per second per second, or (m/s)/s, which equals m/s2.

20. s, min m/s m/s2 m, cm m/s + direction seconds, minutes Measurement
Metric Unit
Symbol
distance
time
speed
velocity
acceleration
m, cm
meters, centimeters
seconds, minutes
s, min
m/s
meters per second
meters per second plus direction
m/s + direction
meters per second per second
m/s2
_D__1 cm T_ 2. 6 s S_ 12m/s V_km/h N A_30m/s2