Transcript Measuring Motion

Chapter 1; Section 1
Road Runner Video
Notes:
Observing Motion
 Reference Point:
Object that appears to stay in place
 Ex: Earth’s surface
You
Landscape
 Motion:
When an object changes position over time when
compared with a reference point
Dancing on the Ceiling
 Fred Astaire's Famous Ceiling Dance.mp4
 Astaire Unwound.mp4
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
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
Section Review Pg 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
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
Section Review Pg 10
 Answers on pg 10 in book
What is Force?
 Chapter 1 Section 2
Forces Act on Objects
 Forces= A push or pull on an object
 Size and direction
 Newton= How force is measured
 SI unit
Activity:
Examples
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:
Unbalanced and Balanced Forces
 Unbalanced Forces=
The object moves (Change in motion)
 Not equal to 0
 Ex. Soccer Ball
 Balanced Force=
the object doesn’t move
 Equal to 0
 Ex. Bird’s nest in a tree
 Ex. Hat resting on your head
Friction: A Force That
Opposes Motion
 Chapter 1, Section 3
The Source of Friction
 Friction: A force that opposes motion between two
surfaces that are touching.
 Friction depends on two things:
1.
Roughness of surfaces- The rougher the surface, the
more friction
Ex. Skating on ice vs. grass
2.
Amount of force- the greater the force the more
friction
Ex. Massive object vs. Non massive object
Activity:
Pg 15: Connect to life…
Types of Friction
 Definition
 Two facts
 3 examples
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
Discussion!
 Ways to reduce friction?
 Ways to increase friction?
Activity:
pg 20 apply
Gravity: A Force of
Attraction
 Chapter 1, Section 4
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
 Earth’s 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
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
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