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PHYSICS 2014
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Sir Isaac Newton Proposed 3 laws of motion in the 1600’s Proposed 3 laws of motion in the 1600’s Laws explain the relationship among forces, matter, and motion Laws explain the relationship among forces, matter, and motion
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Lesson 1 Motion
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Motion An object is in motion if the object changes position relative to a reference point. Once an object’s reference point is known, you can calculate: Speed Speed Velocity Velocity Acceleration Acceleration
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Speed – the distance an object travels divided by the time it takes to travel that distance SPEED= distance/time
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Velocity – the speed of an object with the direction the object is moving in Calculate the same as speed. Measurement units are the same but the direction is added.
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Acceleration – rate at which the velocity of an object changes Acceleration includes: Speeding up Speeding up Slowing down Slowing down Changing direction Changing direction
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GRAVITY The force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface. The force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface.
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Forces Force: a push or pull on an object When an object is speeding up, slowing down or changing direction, a force is acting upon the object
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Types of Forces 1. Balanced Forces *do not change an object’s motion *do not change an object’s motion *all forces acting on the object are equal *all forces acting on the object are equal
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Types of Forces 2. Unbalanced Forces *can cause an object to start moving, stop moving, or change direction *can cause an object to start moving, stop moving, or change direction *one force is greater than another force acting upon the object *one force is greater than another force acting upon the object
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Lesson 2 Newton’s Laws of Motion
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Inertia The First Law is the law of inertia The First Law is the law of inertia Inertia is an objects tendency to resist a change in motion Inertia is an objects tendency to resist a change in motion
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First Law of Motion An object at rest will stay at rest AND An object in motion will stay in motion UNLESS acted upon by an unbalanced force. Examples of forces: push or pull, friction, air resistance Examples of forces: push or pull, friction, air resistance
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Friction Slows an object until it stops Slows an object until it stops Produces heat Produces heat Wears the object down Wears the object down
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Second Law of Motion The force of an object is equal to its mass times its acceleration. F = M x A F = M x A (force) (mass) (acceleration) (force) (mass) (acceleration) The greater the FORCE the greater the acceleration.The greater the FORCE the greater the acceleration. The larger the MASS of an object the greater the force required to accelerate or slow down the objectThe larger the MASS of an object the greater the force required to accelerate or slow down the object
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It’s easier to move a soccer ball than it is to move a brick wall It’s easier to move a soccer ball than it is to move a brick wall
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Third Law of Motion Third Law of Motion For every action there is an equal and opposite reaction. For every action there is an equal and opposite reaction. Consider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push air downwards. Since forces result from mutual interactions, the air must also be pushing the bird upwards
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the direction of the force on the air (downwards) is opposite the direction of the force on the bird (upwards).. the direction of the force on the air (downwards) is opposite the direction of the force on the bird (upwards).. A person paddling a boat A person paddling a boat pushes backward, causing pushes backward, causing the canoe to move forward the canoe to move forward
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What enables us to walk? To move forward parallel to the floor we must push backward on the floor with one foot. By the third law, the floor pushes forward, moving us forward. Then the process is repeated with the other foot, etc. This cannot occur unless there is friction between the foot and floor and on a frictionless surface we would not be able to walk. What enables us to walk? To move forward parallel to the floor we must push backward on the floor with one foot. By the third law, the floor pushes forward, moving us forward. Then the process is repeated with the other foot, etc. This cannot occur unless there is friction between the foot and floor and on a frictionless surface we would not be able to walk.
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Consider the motion of a car on the way to school. A car is equipped with wheels which spin backwards. Consider the motion of a car on the way to school. A car is equipped with wheels which spin backwards. As the wheels spin backwards, they grip the road and push the road backwards. The road must also be pushing the wheels forward. As the wheels spin backwards, they grip the road and push the road backwards. The road must also be pushing the wheels forward. For every action, there is an equal (in size) and opposite (in direction) reaction. Action-reaction force pairs make it possible for cars to move along a roadway surface. For every action, there is an equal (in size) and opposite (in direction) reaction. Action-reaction force pairs make it possible for cars to move along a roadway surface.
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Lesson 3 Work and Energy
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Work Work – the exertion of a force that causes an object to move W = F x D W = F x D (work) (force) (distance) (work) (force) (distance)
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Energy Energy – the ability to do work Work can be thought of as a transfer of energy. Two types of energy: 1. Potential 1. Potential 2. Kinetic 2. Kinetic
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Types of Energy Potential Energy Energy that is stored Energy that is stored Has the potential to do work Has the potential to do work Kinetic Energy Energy in motion (of moving objects) Energy in motion (of moving objects) In process of doing the work In process of doing the work
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Light, Sound and Heat Energy move in Waves
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