2.1 DEFINITIONS AND BASIC UNITS OF MECHANICS

In this section we will deal with two measurement systems: the U.S. customary gravitational system, and the SI absolute system, which uses metric units. Some commonly measured mechanical properties are defined here.

Acceleration

Time rate of change of velocity. It is thus a time rate of change of a time rate of change.

Components

The single individual forces that are the equivalent of the resultant.

Concurrent

Forces whose lines of action or directions pass through a common point, or meet at a common point.

Coplanar

Forces all in the same plane.

Couple

A system of nonconcurrent forces tending to produce rotation about an axis.

Dynamics

Concerns bodies not in equilibrium; i.e., not at rest or with nonuniform motion.

Inertia

A property of matter that causes it to resist change in its motion or its state of rest.

Kinematics

A branch of dynamics that deals only with motions of bodies, not considering forces. It can thus be described as the geometry of motion.

Kinetics

A branch of dynamics that relates the actions of forces to the resulting motions of bodies.

Mass

The measure of the inertia of a body. Mass also initiates gravitational attraction.

Mechanics

The science that deals with forces and their effects on bodies at rest or in motion.

Moment

A force with respect to a point, which is the product of the force and the perpendicular distance from the point to the direction of the force (line of force). The distance...