Ch1: Principles of Statics

Kip

1000 pounds

Statics and Dynamics

2 parts or branches of Engineering Mechanics

Trusses, Centroids, and Friction

3 applications under statics

Concurrent, Parallel, and Non-concurrent

3 force systems under statics

Translation, Rotation, and Plane Motion

3 kinematics under dynamics

Translation, Rotation, and Plane Motion

3 kinetics under dynamics

Free-body Diagram

A sketch of the isolated body which shows only the forces acting upon the body

Solids

Are actually not rigid, they deform under the action of applied forces

Kinematics

Deals with the pure motion of rigid bodies

Kinematics and Kinetics

Divisions or branches of Dynamics

Magnitude

First characteristic of a force

Action Forces

Forces acting on the free body

Vector Addition

Geometric addition used to combine vector quantities

Unity

Is a ratio of units (of the same kind but different in size) containing the required units and those given

Internal effect of a force

Is definitely dependent on its point of application

Fundamental Axioms of Mechanics

Self-evident facts which cannot be proven mathematically but can only be demonstrated to be true

Principle of Transmissibility of a force

States that the external effect of a force on a body is the same for all points of application along its line of action and the internal effect is definitely dependent on its point of application

Axiom 2

States that two equal, opposite, collinear forces are in equilibrium

Dimensionally Homogeneous

The units on each side of the equation must be of the same dimensional form

Direction of force acts along its line of action

Third characteristic of a force

Principles of Mechanics

Are postulated upon several more or less self-evident facts which cannot be proven mathematically but can only be demonstrated to be true

External effects of forces

Are the same for all points of application along its line of action

Reaction Forces

Are those exerted by the free body upon other bodies

Ton

2000 pounds

Applied Forces

Also called action forces

External effects of forces

Are considered in engineering mechanics

Internal effect of a force

Are considered in strength of materials

Force systems and Applications

Divisions or branches of statics

Non-concurrent Force Systems

Forces whose lines of action are neither parallel nor intersect in a common point

Parallel Force Systems

Forces whose lines of action are parallel

Concurrent Force Systems

Forces whose lines of action pass through a common point

Conversion

Is accomplished by multiplying the given term by unity where unity where unity is a ratio of units (of the same kind but different in size) containing the required units and those given

Force System

Is any arrangement where two or more forces act on a body or group of related bodies

Rigid Body

Is defined as a definite amount of matter the parts of which are fixed in position relative to each other

Free Vector

Is defined as one which does not show the point of application of the vector

Localized Vector

Is defined as one which does show the point of application of the vector

Resultant

Is the single force which will produce the same effect as the original forces

Pound

Is the unit of force commonly used in the United States

Internal effect of a force

Is to produce stress and deformation in the body on which the force acts

Force

May be defined as that which changes, or tends to change, the state of motion of a body

Parallelogram Law

One of the fundamental axioms of mechanics

Vector Quantities

Quantities which possess direction as well as magnitude

Scalar Quantities

Quantities which possess magtitude only and can be added arithmetically

Kinetics

Relates motion to the applied forces

Position of its line of action

Second characteristic of a force

Parallelogram Law

The resultant of two forces is the diagonal of the parallelogram formed on the vectors of these forces

Engineering Mechanics

The science which considers the effects of forces on rigid bodies

Non-coplanar

When lines of action of all the forces in a force system don't lie in one plane

Coplanar

When lines of action of all the forces in a force system lie in one plane