Wile E. Coyote If Wile E. Coyote and a bolder fall off a cliff at the same time which do you think will hit the ground first?

 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

 What is more affected by air resistance a school bus or a race car?  Fluid friction opposes motion of objects › Also known as air resistance  Amount of air resistance depends on: › Size of object › Shape of object Self Check Figure 3

 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 Simulation: galileo_pisa_finalv1.2galileo_pisa_finalv1.2

 Free Fall= No air resistance  Free fall can only happen where there is no air › In a vacuum › In space Pg 39 Figure 5 What problem might you have if you were to sky dive on the moon?

 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 ›

 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

 “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”

 Part 1: Objects at Rest › 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 Apply

 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

 “The acceleration of an object depends on the mass of the object and the amount of forced applied”

 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

 a= F/m  F= m X a  M= F/a  Math Break Pg 47

 “ Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.”

 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

 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

 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

 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 3 rd Law › Action force= billiard ball moves › Reaction force= stops cue ball’s motion