Glossary

7.0 Introduction

uniform circular motion

the motion of an object in a circular path at constant speed

7.1 Rotation Angle and Angular Velocity

arc length

[latex]\text{Δ}s[/latex], the distance traveled by an object along a circular path

pit

a tiny indentation on the spiral track moulded into the top of the polycarbonate layer of CD

rotation angle

the ratio of the arc length to the radius of curvature on a circular path:

[latex]\text{Δ}\theta =\frac{\text{Δ}s}{r}[/latex]

radius of curvature

radius of a circular path

radians

a unit of angle measurement

angular velocity

[latex]\omega[/latex], the rate of change of the angle with which an object moves on a circular path

7.2 Angular Acceleration

angular acceleration

the rate of change of angular velocity with time

change in angular velocity

the difference between final and initial values of angular velocity

tangential acceleration

the acceleration in a direction tangent to the circle at the point of interest in circular motion

7.3 Centripetal Acceleration

centripetal acceleration

the acceleration of an object moving in a circle, directed toward the center

ultracentrifuge

a centrifuge optimized for spinning a rotor at very high speeds

7.4 Centripetal Force

centripetal force

any net force causing uniform circular motion

ideal banking

the sloping of a curve in a road, where the angle of the slope allows the vehicle to negotiate the curve at a certain speed without the aid of friction between the tires and the road; the net external force on the vehicle equals the horizontal centripetal force in the absence of friction

ideal speed

the maximum safe speed at which a vehicle can turn on a curve without the aid of friction between the tire and the road

ideal angle

the angle at which a car can turn safely on a steep curve, which is in proportion to the ideal speed

banked curve

the curve in a road that is sloping in a manner that helps a vehicle negotiate the curve

7.5 Relating Angular and Translational Quantities

total linear acceleration

vector sum of the centripetal acceleration vector and the tangential acceleration vector

7.6 Fictitious Forces and Non-inertial Frames: The Coriolis Force

fictitious force

a force having no physical origin

centrifugal force

a fictitious force that tends to throw an object off when the object is rotating in a non-inertial frame of reference

Coriolis force

the fictitious force causing the apparent deflection of moving objects when viewed in a rotating frame of reference

non-inertial frame of reference

an accelerated frame of reference

7.7 Kinematics of Rotational Motion

kinematics of rotational motion

describes the relationships among rotation angle, angular velocity, angular acceleration, and time