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Published byNoel Doyle Modified over 4 years ago

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What is Velocity? What is Acceleration?

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Mrs. Wilk drove to school this morning. Her average speed was 27 mph. What was Mrs. Wilk’s average speed this morning? What was Mrs. Wilk’s average speed this morning? 27mph27mph What was Mrs. Wilk’s velocity? 27mph to school 27mph to school Velocity is defined as: A vector quantity that tells how fast an object is moving and in what direction it is moving A vector quantity that tells how fast an object is moving and in what direction it is moving Speed with direction Speed with direction

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What is a vector quantity? A quantity that includes direction. A quantity that includes direction. How does one know that something is a vector quantity? Boldface type or ½ arrow Boldface type or ½ arrow or v or v

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Example: The speedometer of a car moving northward reads 60 mph. It passes another car traveling southward at 60 mph. Do the cars have the same speed? Yes---60mph Yes---60mph Do the cars have the same velocity? No because they are moving different directions No because they are moving different directions Why is a car’s gauge called a speedometer and not a velociometer? Because it does not show direction Because it does not show direction

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The velocity equation: In words: Velocity = distance / time * with direction Velocity = distance / time * with direction In symbols: V = d/t V = d/t The wheel The wheel d vt

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What is constant speed? Equal distances covered in equal amounts of time Equal distances covered in equal amounts of time What is constant velocity? Constant speed with constant direction Constant speed with constant direction Watch the battery operated car: Constant speed and constant velocity

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What is changing velocity? Watch the battery operated car: Is the speed constant? Is the speed constant? Yes– the car is moving = distances in = time periodsYes– the car is moving = distances in = time periods Is the velocity constant? Is the velocity constant? No– because the direction is constantly changing.No– because the direction is constantly changing.

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There are 4 controls on a car that can change the velocity. Do you know what they are? 1. gas pedal 2. brake pedal 3. steering wheel 4. transmission

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We can change the state of motion of an object by changing: 1. its speed 1. its speed 2. its direction of motion 2. its direction of motion 3. both its speed and direction 3. both its speed and direction Any of these changes is considered a change in an object’s velocity.

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Sometimes we are interested in how fast the velocity is changing. This is called an object’s acceleration. What is acceleration? A rate measuring how fast an object’s velocity is changing per unit of time. A rate measuring how fast an object’s velocity is changing per unit of time.

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The acceleration equation: In words: Acceleration = change in velocity / time Acceleration = change in velocity / time In symbols: a = v / t a = v / t The wheel: The wheel: at v

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OR V f = Final Velocity V i = Initial

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