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7/30/2019 Kinematics and Circular Motion
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Victorena II A. Diesta
Pia Angeli Espartinez
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Refers to a science studying the motion of rotating bodies
without consideration of forces causing the motion.
Examples:
Wheels of vehicles, electric fans, even simple body motionssuch as twirling a finger.
Axis of Rotation- a line where a rotating object rotates
about
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Comparison of definition
of terms:LINEAR MOTIONPosition noting the location of an object with respect to its
reference point.
Displacement the change in position
ROTATIONAL MOTIONPosition choosing a point on the rotating object and
noting the angle that a line from the axis to thispoint make with the reference line.
Displacement
the change in angular position;represented by
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As to distinguish angular displacementoccurring in opposite directions, we willassign the positive sign (+) of angulardisplacement to correspond tocounterclockwise; and negative sign (-)for clockwise.
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LINEAR MOTION
Acceleration - ratio of the change in
velocity to the time it takes for the changeto occur
ROTATIONAL MOTIONAcceleration ratio of change in angular
velocity to the time it takes for the
change to occur
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Positive acceleration doesnt
always mean that the direction is
positive; likewise, negativeacceleration doesnt always mean
the motion is counterclockwise.
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The greek letter alpha is used to
represent angular acceleration.
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ROTATIONAL MOTION
Velocity - ratio of
angular displacementto time;related to how
fast the object rotates
LINEAR MOTION
Velocity ratio of
displacement totime; related to how
fast the object
moves.
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VELOCITY
Angular velocity is positive when the
direction is counter clockwise,negative
when clockwise. The lowercase Greekletter, omega is used to represent
angular acceleration.
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Something to Remember
Rotational Motions which are
counterclockwise are positive quantities
while those which are clockwise arenegative quantities.
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Radian
- a common unit
used in
expressingangular positions
and angular
displacement
It is defined such
that when an object
has rotated by 1
radian, the chosen
point on the body
would have traced
an arc whose lengthis equal to the
radius of the circular
path.
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When the point has completely traced a
circle, it has traveled an arc whose length
is 2(pi)r .Since every arc length traced that
is equal to the radius r corresponds to
angular displacement of 1 rad, we can get
the total angular displacement when the
arc length is 2(pi)r by ratio and proportion.
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