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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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