##### From Electromechanical Design Handbook, Third Edition

## 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...

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