1. Chapter 2 Forces in Motion

2. Gravity and Motion Chapter 2, Section 1
Aristotle Vs. Galileo

3. All objects Fall with the Same Acceleration
Objects fall to the ground at same rate
Acceleration due to gravity = same for all objects
All objects accelerate toward earth at a rate of 9.8 meters per second
9.8 m/s/s
Using the figure pg 37
Math Break pg 37

4. Air Resistance Slows Down Acceleration
Fluid friction opposes motion of objects
Also known as air resistance
Amount of air resistance depends on:
Size of object
Shape of object
Pg 38: reading strategy
Self Check
Figure 3

5. Acceleration Stops at the Terminal Velocity
Net force does not equal 0 = object accelerates downward
Air resistance increases as speed of object increases
Upward force of air resistance increases until it exactly matches the downward force of gravity
This causes net force of 0= Terminal Velocity (Constant Velocity)
Pg 38 Figure 4

6. Free Fall Occurs When There I No Air Resistance
Free Fall= No air resistance
Free fall can only happen where there is no air
In a vacuum
In space
Pg 39 Figure 5
Pg 39 Concept Mapping

7. Orbiting Objects Are In Free Fall
An orbiting object is going forward and falling- It is falling around the earth
Pg 40 Using the figure Figure 7

8. Projectile Motion The curved path an object follows when thrown
Thrown objects and falling objects have the same acceleration
Orbiting objects are examples of projectiles
Projectile objects have two components- horizontal and vertical
Both components are independent of each other

9. Ch 2 Sec 2: Newton’s Laws of Motion

10. Newton’s First Law of Motion
“An object at rest remains at rest and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force”

11. First Law Continued Part 1: Objects at Rest Part 2: Object in Motion
Object will not move until a push or pull is exerted on them
Ex. Plane won’t fly unless pushed by exhaust from engine
Part 2: Object in Motion
Object will move forever at the same speed and in same direction unless some unbalanced force acts on it
Ex. Bumper car stops but you continue to move forward until your seat belt stops you
Pg 44 Real – World Connection
Pg 44 Apply

12. First Law Continued
Friction: Makes it difficult to observance of the first law on everyday objects
Ex. Grass causes a rolling ball to stop
Inertia: Tendency of all objects to resist any change in motion
Ex. Slide toward side of car when driver makes a sharp turn
Mass: Smaller mass has less inertia than object with large mass
Ex. Push car vs. bike
Pg 45 Self Check

13. Newton’s Second Law of Motion
“The acceleration of an object depends on the mass of the object and the amount of forced applied”

14. Second Law Continued Part 1: Acceleration Depends on Mass
Same force= objects acceleration decreases as its mass increases and its acceleration increases as its mass decreases
Ex. Shopping Cart
Part 2: Accelerating Depends on Force
An objects acceleration:
Increases as force increases
Decreases as force decreases

15. Second Law Continued a= F/m F= m X a M= F/a Pg 46 reteaching
Pg 47 math break

16. Newton’s Third Law of Motion
“ Whenever one object exerts a force on a second object, the second object exerts and equal and opposite force on the first.”

17. Newton’s Third Law Continued
All forces act in pairs: Actions and Reactions
Can occur when there is no motion
Ex: Action Force= Body exert force on chair
Reaction force= force exerted by the chair that pushed up on your body
No movement

18. Newton’s Third Law Continued
Force Pairs Do Not Act on the Same Object
Ex. Swimming
Action force = exerted on the water by swimmer’s hands and feet
Reaction force = exerted on the swimmer’s hands and feet by water
The Effect of a Reaction Can be Hard to See
The force of gravity between Earth and a falling object is a force pair
Pg 49 examples
Pg 49 real world connections

19. Momentum Is a Property of Moving Objects
Momentum= Property of a moving object that depends on the object’s mass and velocity
P= m X v
P= Momentum
m=mass
V=velocity
More momentum= harder to stop or change direction

20. Momentum Continued Law of Conservation of Momentum:
Two or more objects interact, may exchange momentum, but total amount stays the same
Ex. Billiards or Bowling
Momentum and Newton’s 3rd Law
Action force= billiard ball moves
Reaction force= stops cue ball’s motion