POE Vocab Lesson 2-1

Parts 1 and 2

Cable

A strong rope, usually made of metal, designed to have great tensile strength and to be used in structures.

Centroid

The geometric center of an area.

Compression Force

A body subjected to a push.

Concurrent Force Systems

A force system where all of the forces are applied at a common point on the body or having their lines of action with a common intersection point.

Cross-Sectional Area

A surface or shape exposed by making a straight cut through something at right angles to the axis.

Direction

The direction of a vector is defined by the angle between a reference axis and the arrow's line of direction.

Fixed Support

A support that prevents translation and rotation in a beam.

Flange

A broad ridge or pair of ridges projecting at a right angle from the edge of a structural shape in order to strengthen or stiffen it.

Free Body Diagram

A diagram used to isolate a body from its environment, showing all external forces acting upon it.

Gusset

A plate or bracket for strengthening an angle in framework.

Joint

The connection points of members of a truss

Magnitude

The absolute value of a number

Member

Slender straight pieces of a truss connected by joints.

Method of Joints

A method of analysis of trusses which constructs free body diagrams of each joint and determines the forces acting in that joint by considering equilibrium of the joint pin.

Moment

The turning effect of a force about a point equal to the magnitude of the force times the perpendicular distance from the point to the line of action from the force.

Moment of Inertia

A mathematical property of a cross section that is concerned with a surface area and how that area is distributed about a centroidal axis.

Newton's First Law

Every body or particle continues at a state of rest or uniform motion in a straight line, unless it is compelled to change that state by forces acting upon it.

Newton's Second Law

The change of motion of the body is proportional to the net force imposed on the body and is in the direction of the net force.

Newton's Third Law

If one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object.

Pinned Support

A support that prevents translation in any direction

Planar Truss

A truss that lies in a single plane often used to support roofs and bridges.

Resultant Force

The resultant of a system of force is the vector sum of all forces.

Roller Support

A support that only prevents a beam from translating in one direction.

Scalar

A physical quantity that has magnitude only.

Sense

The sense of a vector is the direction of the vector relative to its path and indicated by the location of the arrow.

Simple Truss

A truss composed of triangles, which will retain its shape even when removed from supports.

Static Equilibrium

A condition where there are no net external forces acting upon a particle or rigid body and the body remains at rest or continues at a constant velocity.

Statically Indeterminate

A structure or body which is over-constrained such that there are more unknown supports than there are equations of static equilibrium.

Structure

Something made up of interdependent parts in a definite pattern of organization, such as trusses, frames, or machines.

Tension Force

A body subjected to a pull.

Vector Quantity

A quantity that has both a magnitude and direction.