Radian

An arc of a circle equal in length to the radius; or the angle at the center measured by the arc.

Radius of Gyration

The distance from the reference at which all of the area can be considered concentrated that still produces the same moment of inertia. Numerically it is equal to the square root of the moment of inertia, divided by the area.

Rainfall

PrecipitationProcess by which water in liquid or solid state (rain, sleet, snow) is discharged out of the atmosphere upon a land or water surface. in the form of water (usage includes snow).

Ramming

A percussive hammer is attached to an open end casing, which is driven through the ground. The spoil within the casing is removed to leave an open casing.

Ranking

To assign a relative position to competing items.