ES AMACE TERMS

SCALAR

magnitude only (mass, speed, volume, temperature)

VECTOR

Has magnitude and

direction i.e.

Force,

displacement, velocity,

acceleration

Fixed or bound vectors

vectors have well defined points of application that cannot be changed

without affecting an analysis.

Freevectors

may be freely moved in space without changing their effect on an analysis.

sliding vectors

may be applied anywhere along their line of action without affecting an

analysis.

force

action of one body

on another; characterized

by its point of application ,

magnitude , line of action ,

and sense

resultant force

developed on the body in that direction

If a support prevents the translation of a body in a given direction, then a force is ______________________

couple moment

If rotation is prevented, a __________________ is exerted on the body

1

number of unknowns in a support cable

1

number of unknowns in a roller support

2

number of unknowns in a pin support

3

number of unknowns in a fixed support

completely constrained

Rigid body could not possibly move

partially constrained

Constraints are not sufficient to keep the body from moving

statically determinate

When the unknowns could be solved by equations of equilibrium

statically indeterminate

When there are more unknowns than equilibrium equations

truss

a structure composed of slender members joined together at their end points.

planar truss

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

extremities only

Truss members are connected at their _________________; thus no member is continuous through a joint.

true

t/f:

no member is continuous through a joint

joints

in a truss loads must be applied at the

zero force members

When multiple members are connected at a joint, and there is no external force applied to that joint

plane surveying

the study of the internal effect of external forces applied to structural members.

stress

defined as the strength of a material per unit area.

stress

defined as the strength of a material per unit area.

normal, shear, bearing

Simple stress can be classified as either the following:

Normal stress

develops when a force is applied perpendicular to the cross-sectional area of the material.

tensile or compressive

Normal stress is either

Shear Stress

is developed if the applied force is parallel to the resisting area

Tangential Stress

Shear stress is also known as

Bearing stress

is the contact pressure between separate bodies.

Strain

the ratio of the change in length caused by the applied force, to the original length.

hookes law

The law stating that the stress of a solid is directly proportional to the strain applied to it.

elastic limit

the limit beyond which the material will no longer go back to its original shape when the load is removed, or it is the maximum stress that may be developed such that there is no permanent or residual deformation when the load is entirely removed.

Yield Point

point at which the material will have an appreciable elongation or yielding without any increase in load.

Ultimate or Tensile Strength

the maximum ordinate in the stress-strain diagram.

rupture or breaking strength

the strength of the material just before it ruptures/breaks.

working stress

defined as the actual stress of a material under a given loading.

allowable stress

The maximum safe stress that a material can carry

factor of safety

The ratio of this strength (ultimate or yield strength) to allowable strength

centroid

is the term used to denote the center of gravity of weightless figures such as line, area, and volume.

radius of gyration

distance from the axis of rotation to a point where the body's mass could be concentrated without altering its rotational characteristics

3rd

a triangular uniform load will yield a moment diagram with a curve of what degree

flexure

stresses caused by bending moment

false

t/f:

continuous beam is statically determinate

zero

the bending stress in the neutral axis is assumed to be

squared property

used to determine span of a small parabola cut from a bigger parabolic figure

moment of inertia

measures how much resistance to bending a cross sectional area has

less

a beam with a greater modulus of elasticity will deflect ___________

concentrated load

A kind of load that acts over a small distance that it can be assumed to act at a

point

concurrent validity

Force system whose lines of action pass through a common point

reaction force

Force that inhibits change in the state of movement of a body

triangular load

The intensity of loading increases or decreases at a constant rate

strength of materials

Deals with the relation between externally applied loads and internal effects

continuous beam

A type of beam with at least three or more supports

Centroidal Axis

An axis passing through the centroid of an area is known as a __________

Concurrent, Coplanar

The action lines of all the forces are in the same plane and intersect a

common point

Parallelogram Law

The resultant of two forces which is the diagonal formed on the vectors of this

force.

Newton's 3rd Law

Each action has a reaction equal in magnitude and opposite in direction

Moment

The measure of tendency of a force to make a rigid body rotate about a fixed

axis

Varignon's Theorem

This theorem states that the moment of a resultant of two children concurrent

forces about any point is equal to the algebraic sum of the moments of its

components about the same point.

Length

Strain is deformation divided by _______

Zero Force member

Some members in the truss which cannot carry load

System of Forces

When several forces act in a given situation

Principle of Transmissibility

The external effect of a force in a rigid body is the same for all point along its

line of action

Rubber

Which of the following is a "non-hookean" material

Newton's First Law of Motion

If the resultant force acting on a particle is zero, the particle remains at rest (if

originally at rest) or will move with constant speed in a straight line (if originally in

motion)

Shear and Bending Moment Diagram

A diagram which shows the variations of the axial load for all sections in the span of a

beam

Equilibrium

A condition in which the resultants of all forces acting on the body is zero.

Statics of rigid bodies

the study of materials, objects, or particles at rest

or moving under constant velocity

Rigid Body

combination of large number of particles in which all particles remain at a fixed

distance from one another before and applying a load

kN m

SI unit for bending moment

Weight

Refers to the gravitational force (attraction) of the earth acting on a body.

Neutral Axis

In a beam, which layer is neither elongated nor shortened during bending?

3

In a body loaded under plane stress conditions, how many independent stress

components are present?