1. Chapter 10
Section 1 Measuring Motion
Objectives
Explain the relationship between motion and a frame of reference.
Relate speed to distance and time.
Distinguish between speed and velocity.
Solve problems related to time, distance, displacement, speed, and velocity.

2. Observing Motion Chapter 10
Section 1 Measuring Motion
Observing Motion
Motion is an object’s change in position relative to a reference point.
Displacement is the change in the position of an object.
Distance measures the path taken.
Displacement is the change of an object’s position. Displacement must always indicate direction.

3. Chapter 10
Section 1 Measuring Motion
Motion

4. Distance vs. Displacement
Chapter 10
Section 1 Measuring Motion
Distance vs. Displacement

5. Speed and Velocity Chapter 10
Section 1 Measuring Motion
Speed and Velocity
Speed is the distance traveled divided by the time interval during which the motion occurred. Speed describes how fast an object moves.
Speed measurements involve distance and time.
The SI units for speed are meters per second (m/s).
When an object covers equal distances in equal amounts of time, it is moving at a constant speed.

6. Chapter 10
Section 1 Measuring Motion
Speed

7. Speed and Velocity, continued
Chapter 10
Section 1 Measuring Motion
Speed and Velocity, continued
Speed can be studied with graphs and equations.
Speed can be determined from a distance-time graph. When an object’s motion is graphed by plotting distance on the y-axis and time on the x-axis, the slope of the graph is speed.

8. Speed and Velocity, continued
Chapter 10
Section 1 Measuring Motion
Speed and Velocity, continued
Average speed is calculated as distance divided by time.
Equation for Average Speed
Instantaneous speed is the speed at a given point in time.

9. Chapter 10
Section 1 Measuring Motion
Math Skills
Velocity Metal stakes are sometimes placed in glaciers to help measure a glacier’s movement. For several days in 1936, Alaska’s Black Rapids glacier surged as swiftly as 89 meters per day down the valley. Find the glacier’s velocity in m/s. Remember to include direction.
List the given and the unknown values.
Given:
m down the valley
Unknown:

10. Math Skills Chapter 10 2. Perform any necessary conversions.
Section 1 Measuring Motion
Math Skills
2. Perform any necessary conversions.
To find the velocity in meters per second, the value for time must be in seconds.

11. Math Skills Chapter 10 3. Write the equation for speed.
Section 1 Measuring Motion
Math Skills
3. Write the equation for speed.
4. Insert the known values into the equation, and solve.

12. Speed and Velocity, continued
Chapter 10
Section 1 Measuring Motion
Speed and Velocity, continued
Velocity is the speed of an object in a particular direction.
Velocity describes both the speed and the direction.
Combine velocities to determine the resultant velocity.

13. Speed and Velocity, continued
Chapter 10
Section 1 Measuring Motion
Speed and Velocity, continued

14. Chapter 10
Section 1 Measuring Motion
Velocity
Visual Concept

15. Chapter 10
Section 2 Acceleration
Objectives
Describe the concept of acceleration as a change in velocity.
Explain why circular motion is continuous acceleration even when the speed does not change.
Calculate acceleration as the rate at which velocity changes.
Graph acceleration on a velocity-time graph.

16. Acceleration and Motion
Chapter 10
Section 2 Acceleration
Acceleration and Motion
Acceleration is the rate at which velocity changes over time.
An object accelerates if its speed, direction, or both change.

17. Chapter 10
Section 2 Acceleration
Acceleration

18. Acceleration and Motion
Chapter 10
Section 2 Acceleration
Acceleration and Motion
Acceleration can be a change in speed.
Acceleration can be a change in direction.
Uniform circular motion is constant acceleration.

19. Centripetal Acceleration
Chapter 10
Section 2 Acceleration
Centripetal Acceleration

20. Calculating Acceleration
Chapter 10
Section 2 Acceleration
Calculating Acceleration
Acceleration is the rate at which velocity changes.
Acceleration Equation (for straight-line motion)
In SI units, acceleration is measured in meters per second per second (m/s/s) or m/s2.

21. Chapter 10
Section 2 Acceleration
Math Skills
Acceleration A flowerpot falls off a second- story windowsill. The flowerpot starts from rest and hits the sidewalk 1.5 s later with a velocity of 14.7 m/s. Find the average acceleration of the flowerpot.
1. List the given and the unknown values.
Given:
Unknown:

22. Math Skills, continued Chapter 10
Section 2 Acceleration
Math Skills, continued
2. Write the equation for acceleration.
3. Insert the known values into the equation, and solve.

23. Calculating Acceleration, continued
Chapter 10
Section 2 Acceleration
Calculating Acceleration, continued
Acceleration can be determined from a velocity-time graph.

24. Graphical Representations of Acceleration
Chapter 10
Section 2 Acceleration
Graphical Representations of Acceleration

25. Chapter 10
Section 3 Motion and Force
Objectives
Explain the effects of unbalanced forces on the motion of objects.
Compare and contrast static and kinetic friction.
Describe how friction may be either harmful or helpful.
Identify ways in which friction can be reduced or increased.

26. Balanced and Unbalanced Forces
Chapter 10
Section 3 Motion and Force
Balanced and Unbalanced Forces
Force is an action exerted on a body in order to change the body’s state of rest or motion. Force has magnitude and direction.
The net force is the combination of all forces acting on an object.
Objects subjected to balanced forces either do not move or move at constant velocity.
An unbalanced force must be present to cause any change in an object’s state of motion or rest.

27. Chapter 10
Section 3 Motion and Force
Force

28. The Force of Friction Chapter 10
Section 3 Motion and Force
The Force of Friction
Friction is a force that opposes motion between two surfaces that are in contact.
Friction opposes the applied force.

29. The Force of Friction, continued
Chapter 10
Section 3 Motion and Force
The Force of Friction, continued

30. The Force of Friction Chapter 10
Section 3 Motion and Force
The Force of Friction
Static friction resists the initiation of sliding motion between two surfaces that are in contact and at rest.
Kinetic friction opposes the movement of two surfaces that are in contact and are sliding over each other.
Static friction is greater than kinetic friction.
There are many different types of kinetic friction, such as sliding friction and rolling friction.
Fluid friction, such as air resistance, also opposes motion.

31. Chapter 10
Section 3 Motion and Force
Types of Friction

32. Frictional Forces and Acceleration
Chapter 10
Section 3 Motion and Force
Frictional Forces and Acceleration

33. Friction and Motion Chapter 10 Friction can be helpful or harmful.
Section 3 Motion and Force
Friction and Motion
Friction can be helpful or harmful.
Friction is necessary to roll a vehicle or hold an object.
However, friction can also cause excessive heating or wear of moving parts.
Harmful friction can be reduced.
Helpful friction can be increased.

34. Ways to Reduce or Increase Friction
Chapter 10
Section 3 Motion and Force
Ways to Reduce or Increase Friction