- angular velocity
- $\omega $, the rate of change of the angle with which an object moves on a circular path

- arc length
- $\text{\Delta}s$, the distance traveled by an object along a circular path

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

- center of mass
- the point where the entire mass of an object or of a system of objects can be thought to be concentrated

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

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

- centripetal force
- any net force causing uniform circular motion

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

- fictitious force
- a force having no physical origin

- gravitational constant,
*G* - a proportionality factor used in the equation for Newton’s universal law of gravitation; it is a universal constant—that is, it is thought to be the same everywhere in the universe

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

- 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

- microgravity
- an environment in which the apparent net acceleration of a body is small compared with that produced by Earth at its surface

- Newton’s universal law of gravitation
- every particle in the universe attracts every other particle with a force along a line joining them; the force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them

- non-inertial frame of reference
- an accelerated frame of reference

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

- radians
- a unit of angle measurement

- radius of curvature
- radius of a circular path

- rotation angle
- the ratio of the arc length to the radius of curvature on a circular path: $\text{\Delta}\theta =\frac{\text{\Delta}s}{r}$

- ultracentrifuge
- a centrifuge optimized for spinning a rotor at very high speeds

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