Engineering Mechanics
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.
