Circular Motion Vocabulary

Axis

the straight line around which an object may rotate or revolve

centrifugal force

an apparent outward force on a rotating or revolving body ("center-fleeing") Not a real force.

centripetal force

a center-directed force that causes an object to move in a curved (sometimes circular) path ("center-seeking")

centripetal acceleration

acceleration directed toward the center of the circle....rate at which the direction of the moving object changes

frequency

the number of rotations or revolutions per unit of time

linear speed

the path distance moved per unit of time

period

the time it takes for one full rotation or revolution

revolution

motion of an object turning around an axis outside (or external to) the object

rotation

the spinning motion that takes place when an object rotates about an axis located within the object (spin)

rotational speed

the number of revolutions per unit of time "angular speed

tangential speed

the speed of an object moving along a circular path "linear speed

tangent

perpendicular to the radius of the circle

acceleration

rate at which linear speed changes

torque

a quantity that measures the ability of a force to rotate an object around some axis

?

rotational speed symbol

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Greek letter "Tau"....symbol for torque

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Symbol for period

f

symbol for frequency

Hz (Hertz)

unit for frequency

s (seconds)

unit for period

N?m

unit for torque (newton-meter)

rps (rotations per second)
rpm (rotations per minute)

unit for rotational speed

rotational inertia (moment of inertia)

property of matter which resists changes in rotational motion

I

symbol for rotational inertia ( moment of inertia)

requirements for 100% equilibrium (non-accelerated motion)

1. No net torque acting on an object
2. No net force acting on an object

L

symbol for angular momentum

conservation of angular momentum

When no net external torque is acting on one or more objects....the angular momentum (L) is conserved.
Meaning...if rotational inertia changes for an object while it is spinning...the rotational speed changes so that the momentum value is conserved.

m/s

unit for tangential speed

translational motion

straight line motion

rotational motion

circular motion (motion on a complete circular path or a partial circular path)

center of gravity

The point at the center of an object's weight distribution (may be located where no material exists, as in a boomerang or a wheel)

Uniform circular motion

circular motion that has constant rotational speed but experiences rotational acceleration because the object is continually changing its direction