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Published byAsa Silman Modified over 2 years ago

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May the Force Be With You!

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What is FORCE? A push or pull on an object Causing resting objects to move Causing moving objects to accelerate

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Two Main Force Types Balanced Forces – Two Forces – Opposite directions – Both are equal in value – No movement (stationary) Unbalanced Forces – Two Forces – One greater than the other – Opposite directions – Movement

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Newton’s 3 Laws of Motion

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1 st Law of Motion The Law – Objects at rest remain at rest or objects in motion remain in motion unless acted on by a force AKA – Law of INERTIA

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1 st Law of Motion Inertia—force that is resistant to the direction of motion Concept—unbalanced forces Ex: – inertia belts (seat belts) – Space ships going through space

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2 nd Law of Motion The Law – The acceleration of a body depends on the ratio of the acting force to the mass of the body Concept – Unbalanced forces AKA – The force formula

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Force Formula Force = mass * acceleration F= m*a F= force (unit = Newton) m= mass (unit = kg) a= acceleration (unit m/s 2

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Force Example Problems #1 How much force is needed to accelerate a 500-kg car at a rate of 4 m/s/s? #2 A 50-kg object is accelerating at a rate of 2 m/s/s, what is the force that caused this acceleration?

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3 rd Law of Motion The Law – For every action there is an equal but opposite reaction Concept – Balanced Forces Ex – Stationary Objects – Rockets being launched

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Applying the 3 rd Law If Rico kicked a ball with 100-N of force, how much force did the ball exert on Rico?

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What is Friction? Is a force that resist motion and can cause heat Allows us to walk, drive a car, play sports Lubricants help reduce friction

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4 Types of Friction Static Friction – Friction force on stationary objects – Ex: book sitting on desk Sliding Friction – Friction acting on objects sliding over a surface – Ex: pushing a box Rolling Friction – Friction acting on objects that are rolling – Ex: car tired Fluid Friction – Friction acting on objects going through a fluid – Fluid—liquid or gas – Ex: swimming or air resistance

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ID the type of Friction

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What is Gravity? A force that acts between masses Acts downward Acceleration due to gravity (on Earth)= 9.8 m/s/s

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What is Air Resistance? Force that slows down falling objects Factors – Atmosphere – Surface area of object Acts upward

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Gravity and Air Resistance: A Relationship They are opposite forces Gravity goes down Air resistance acts up Follows Newton’s 3 rd Law of Motion

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Feather vs. Rock EARTH – Feather floats down – Rock falls at 9.8 m/s/s – Why? Air Resistance Moon or Vacuum – Feather and rock fall at the same rate – WHY? No air so no air resistance

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Projectile Motion The motion of falling objects throw forward Two forces – Gravity – Forward velocity Gravity acts down Velocity acts forward Forms a curve path

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Weight Is the force of gravity acting on an object Weight Formula Weight = mass * gravity F g = m * g F g = weight (unit = N) m= mass (unit = kg) g= gravity (9.8 m/s/s )

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Weight Example Problems #1 If a 20 kg dude is on Earth, what is his weight? #2 A rock on Earth has a weight of 1000 N, what is the rock’s mass?

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