Engineering Mechanics

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force

changes the state of motion of a body

newton

unit of force

statics

forces on rigid bodies which are and remain at rest

length, mass, force and time

four fundamental quantities

sliding vector

has a unique line of action in space but not a unique point of application.

particle

is a body of negligible dimensions.

resultant force

is a single force that represents the net effect of a force system.

non-coplanar

lines of action do not lie in one plane or in different places

coplanar

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

non-concurrent forces

lines of actions neither are parallel nor intersect in a common point

F

magnitude of the force in the formula

characteristics of a force

magnitude, position of its line of action and direction

free vector

one which does not show the point of application of the vector

scalar

quantities which possess magnitude only and can be added arithmetically.

newton-meter

standard unit of measure of moment of a force

principle of transmissilibiy

the external effect of a force of a body is the same for all points of application along its line of action

action/applied forces

the forces acting on the free body

varignon's theorem

the moment about a point or an axis caused by force system is equal to the sum of the moments about the same point or axis produced by its resultant force.

kinematics and kinetics

translation, rotation and plane motion

applications

trusses, centroids and friction

statics and dynamics

two parts of engineering mechanics

trusses, centroids and friction

under applications

concurrent, parallel and non-concurrent

under force systems

translation, rotation and plane motion

under kinematics and kinetics

pound (lb)

unit of force in US

kinematics and kinetics

2 subbranches of dynamics

rigid

A body is considered _____ when the change in distance between any two of its points is negligible for the purpose at hand.

2

For two-dimensional problems, only ___ coordinates are required.

force system

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

non-concurrent forces

are two or more forces whose magnitudes are equal but act in opposite directions with a common line of action.

vectors

arithmetical addition was applied to quantities which possess direction as well as magnitude; can be represented geometrically

concurrent forces

forces whose lines of action pass through a common point

mass

is a measure of the inertia of a body, which is its resistance to a change of velocity. It can also be thought of as the quantity of matter in a body.

time

is the measure of the succession of events and is a basic quantity in dynamics. It is not directly involved in the analysis of statics problems.

negative moment

sign convention of counter-clockwise turning

parallelogram and triangle method

2 graphical methods

dimensions

In mechanics we use four fundamental quantities called __________.

moment arm (d)

distance between the moment center and line of action

parallel force systems

forces whose lines of action are parallel

M = f x d

formula of moment of a force

d

moment arm in the formula

dynamics

motion of rigid bodies caused by the forces acting upon them

free-body diagram

a sktech of the isolated body which shows only the forces acting upon the body

concurrent forces

are two or more forces whose lines of action intersect at the same point to cause rotation.

engineering mechanics

science that considers the effects of forces on rigid bodies

localized vector

shows the point of application of the vector

positive moment

sign convention of clockwise turning

force systems and applications

2 subbranches of statics

3

For three-dimensional problems, ____ independent coordinates are needed.

Triangle Method

Head-to-Tail Addition

significant digits

The accuracy of the final result depends on the least accurate figure used in the computation.

parallelogram law

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

force systems

concurrent, parallel and non-concurrent

rigid body

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

force

is the action of one body on another. A _____ tends to move a body in the direction of its action. The action of a________ is characterized by its magnitude, by the direction of its action, and by its point of application. Thus it is a vector quantity.

space

is the geometric region occupied by bodies whose positions are described by linear and angular measurements relative to a coordinate system.


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