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Forces and Newton

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Forces A Force is a push or a pull. Examples include Examples include Gravity Gravity Contact Force Contact Force Friction Friction Magnetic force Magnetic force Electrical force Electrical force

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Balanced or Unbalanced Forces can be Which side will win?????

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Video Clips Play Push and Pull clip – 3:14 Play Push and Pull clip – 3:14 Play (You may need to log into United Streaming)

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Balanced Forces Balanced Forces do NOT change the object’s motion

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Unbalanced Forces cause objects to Start moving Start moving Stop moving Stop moving Change direction Change direction

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Unbalanced Forces When in the opposite direction, the box moves the direction of the larger force.

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WORK The amount of force used to move an object. Work is done anytime force causes an object to move. Work is not done when there is no motion.

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Quiz A push or pull is called a ______ A push or pull is called a ______ When two equal forces are acting on an object in opposite directions they are _________ forces When two equal forces are acting on an object in opposite directions they are _________ forces When forces are unequal they are _________ forces. When forces are unequal they are _________ forces. Forces are described in strength and ________ Forces are described in strength and ________ A. Force B. Direction C. Balanced D. Unbalanced

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Sir Isaac Newton (1642 - 1727) His ideas are built upon the ideas of Galileo. Newton's three Laws of Motion are general, universal LAWS that explain a wide range of situations. (Newton also invented Calculus and the reflecting telescope).

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1 st Law of Motion (Law of Inertia) An object at rest will stay at rest, and an object in motion will stay in motion at constant velocity, unless acted upon by an unbalanced force.

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1 st Law Inertia is the tendency of an object to resist changes in its velocity: whether in motion or motionless. Inertia is the tendency of an object to resist changes in its velocity: whether in motion or motionless. These pumpkins will not move unless acted on by an unbalanced force.

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The car hits the wall and stops, but the person keeps on going because he is not part of the car. How can the person become part of the car?

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Video Clips Play Newton’s 1 st Law of Motion clip (2:13) Play Newton’s 1 st Law of Motion clip (2:13) Play (United Streaming)

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Newton’s second law shows how force, mass, and acceleration link together. Newton’s second law shows how force, mass, and acceleration link together. The 2 nd law shows that both the size of the force and the mass of the object affect the object’s acceleration. The 2 nd law shows that both the size of the force and the mass of the object affect the object’s acceleration. Force is measured in a unit Newton (N). Force is measured in a unit Newton (N). Newton’s Ideas Continued

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2 nd Law

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F = Force F = Force m = Mass m = Mass a = Acceleration a = Acceleration

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2 nd Law (F = m x a) How much force is needed to accelerate a 1400 kilogram car 2 meters per second/ second? Write the formula Write the formula F = m x a Fill in given numbers and units Fill in given numbers and units F = 1400 kg x 2 meters per second/second Solve for the unknown Solve for the unknown 2800 kg-meters/second/second or 2800 N

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2 nd Law Click below to learn more. http://www.youtube.com/watch?v=UhCG0qo Y9Dc http://www.youtube.com/watch?v=UhCG0qo Y9Dc http://www.youtube.com/watch?v=UhCG0qo Y9Dc http://www.youtube.com/watch?v=UhCG0qo Y9Dc

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Newton’s Third Law is often called the action-reaction in action law. Newton’s Third Law is often called the action-reaction in action law. Newton’s Ideas Continued

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3 rd Law For every action, there is an equal and opposite reaction. For every action, there is an equal and opposite reaction.

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Newton’s 3rd Law in Nature Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. In turn, the water reacts by pushing the fish forwards, propelling the fish through the water. Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. In turn, the water reacts by pushing the fish forwards, propelling the fish through the water. The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards). The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards).

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3 rd Law Flying gracefully through the air, birds depend on Newton’s third law of motion. As the bird pushes down on the air with their wings, the air pushes their wings up and gives them lift.

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3 rd Law The reaction of a rocket is an application of the third law of motion. Various fuels are burned in the engine, producing hot gases. The hot gases push against the inside tube of the rocket and escape out the bottom of the tube. As the gases move downward, the rocket moves in the opposite direction.

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Review 3 Laws of Motion http://www.youtube.com/watch?v=i H48Lc7wq0U http://www.youtube.com/watch?v=i H48Lc7wq0U

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