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