Measuring Motion

1
Measuring Motion

• Chapter 1 Section 1

Road Runner Video Notes
2
Observing Motion

• Reference Point
• Object that appears to stay in place
• Ex Earths surface
• You
• Landscape
• Motion
• When an object changes position over time when
  compared with a reference point

3
Dancing on the Ceiling

• Fred Astaire's Famous Ceiling Dance.mp4
• Astaire Unwound.mp4

4
Speed Depends on Distance and Time

• Speed The rate an object moves
• How long it takes an object to move over time
• Average Speed total distance/ total time
• SI unit for speed meters per second (m/s)
• Activity
• Math Break pg 5

5
Velocity Direction Matters

• Velocity The speed of an object in a specific
  direction
• Planes velocity 600 km/h south
• Activity Self Check pg 6
• Change in velocity change in speed or direction
• Combining Velocities
• Combine two velocities in same direction add
  together
• Combine two velocities in opposite directions
  subtract smaller velocity from larger velocity

6
Section Review Pg 7
7
Acceleration

• Acceleration The rate at which velocity changes
• Activity Predictions 1. 2. 3.
• Calculating acceleration
• Final velocity Starting Velocity
• Time it takes to change velocity
• Meters per second per second m/s/s m/s2
• Activity Math Break
• Acceleration When velocity increases
• Deceleration When velocity decreases
• Activity List four examples

8
Acceleration Continued

• Circular motion Continuous Acceleration
• Centripetal Acceleration Change direction in a
  circle, changes velocity
• Figure 5
• Graphing Acceleration
• Acceleration positive because velocity increases
  as time passes (Graph goes up)
• Deceleration Graph goes down

9
Section Review Pg 10

• Answers on pg 10 in book

10
What is Force?

• Chapter 1 Section 2

11
Forces Act on Objects

• Forces A push or pull on an object
• Size and direction
• Newton How force is measured
• SI unit
• Activity
• Examples

12
Forces in Combination

• Net Fore The combination of forces on an object
• Forces in the same direction Added Together
• Forces in the opposite direction Subtracted from
  one another
• Subtract the smaller force from the larger
• Activity
• Figure 8
• Pg 13 Self Check

13
Unbalanced and Balanced Forces

• Unbalanced Forces
• The object moves (Change in motion)
• Not equal to 0
• Ex. Soccer Ball
• Balanced Force
• the object doesnt move
• Equal to 0
• Ex. Birds nest in a tree
• Ex. Hat resting on your head

14
Friction A Force That Opposes Motion

• Chapter 1, Section 3

15
The Source of Friction

• Friction A force that opposes motion between two
  surfaces that are touching.
• Friction depends on two things
• Roughness of surfaces- The rougher the surface,
  the more friction
• Ex. Skating on ice vs. grass
• Amount of force- the greater the force the more
  friction
• Ex. Massive object vs. Non massive object
• Activity
• Pg 15 Connect to life

16
Types of Friction

• Definition
• Two facts
• 3 examples

17
Types of Friction

• Sliding Friction- The friction of sliding an
  object across another object.
• Ex. Sliding a dresser on the floor or sledding
  down a hill
• Rolling Friction- The friction between wheels and
  the surface they are rolling on
• Ex. Pushing a grocery cart or roller skating
• Fluid Friction- The friction opposes the motion
  of objects traveling through a fluid (fluid may
  be gas or liquid)
• Ex. Swimming through water or a plane flying in
  the air
• Static Friction- Friction that keeps an object
  stationary
• Ex. Pushing on a wall

18
Discussion!

• Ways to reduce friction?
• Ways to increase friction?
• Activity
• pg 20 apply

19
Gravity A Force of Attraction

• Chapter 1, Section 4

20
All Matter Is Affected by Gravity

• Gravity The force between two objects due to
  their masses
• All objects experience an attraction toward all
  other objects
• Earths gravitational force is large pulls
  everything toward center of earth
• Ex. Chair stays in place
• Ex. Dropped objects fall to earth and not toward
  you

21
The Law of Universal Gravitation

• Sir Isaac Newton
• Law All object attract each other and the force
  depends on the objects mass and distance
• Gravitational force increases when mass increases
• Ex. Cat is easier to pick up than elephant
• Gravitational force decreases when distance
  increases
• Ex. Planets
• Activity
• Pg 24 Activity

22
Weight Is a Measure of Gravitational Force

• Weight A measure of the gravitational force
  exerted on an object
• Mass Amount of matter in an object (value does
  not change)
• Gravity is a force and is measured in Newton's
• 100 g is about 1 N