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Motion

the change of position in time

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Displacement

the directed change of an object's position

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Velocity

the time rate of change of displacement

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Acceleration

the time rate of change of velocity

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Objects that fall freely near the surface of the Earth...

are uniformly accelerated by gravity

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"Zero-time"

the time when we begin the event

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"Zero-position"

the specific place where we begin measuring

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Displacement in measured in...

units of length (such as meters or inches)

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In the graph in Section 2.2 (pg 15), the displacement of the object between times t1 and t2 is given by the relationship

d=d2-d1 (we are not primarily concerned about the exact path taken by the object between these points. We assume that the magnitude of the displacement is given by the length of a straight line between d1 and d2 along the axis representing position)

###
Displacment is a ___quantity because

vector, because in addition to magnitude, it has direction.

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The magnitude of displacement is known as

distance

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When the displacement between two points of time (t1 and t2) is positive, that means

its magnitude is measured in the positive direction

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When the displacement between two points of time (t1 and t2) is negative, that means

the displacement is negative, and its magnitude is measured in the negative direction

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Elapsed time can be given by the relationship

t=t1-t2

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Average Velocity=

(slope) d/t (measured in units such as meters per second (m/s), or miles per hour (mph))

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What does average velocity indicate?

how rapidly the position of the object (d) has changed over the time interval (t)

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What type of quantity is velocity?

A vector quantity, because it has both magnitude and direction

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What is the magnitude of velocity?

Speed

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With velocity, we can use positive and negative signs to represent:

motion in opposite directions

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Instantaneous Velocity

the slope of a line drawn tangent to the graph at that point

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The slope of the velocity-time graph is given by the relationship

Δv/t

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What does Δv/t represent?

acceleration, measured in units like meters/seconds^2 (m/s^2)

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When the slope of a velocity-time graph is straight,

the acceleration in this case is constant or uniform.

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Equation to find the uniform acceleration of a velocity-time graph

a=Δv/t

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Acceleration is a ____quantity because

vector, because it has both magnitude and direction.

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A positive acceleration means that

the velocity of an object is becoming more positive with time

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A negative acceleration means that

the velocity of the object is becoming more negative with time.

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Positive displacement

the object traveled the distance in the positive direction

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How to calculate displacement:

Find the area underneath the line in a velocity-time graph. (add the difference displacements for all sections underneath the graph)

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