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Engineering Mechanics Statics Engineering

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Engineering Mechanics Statics Engineering Powered By Docstoc
					Engineering Mechanics
       Statics


       ECS221
      A. J. Levy
    Course Structure

 M,W lecture + F clinic or exam
 Graded homework (13%)

 Four class exams (54%)

 Final exam (33%)

 Course evaluation
Introduction
Primitive concepts
 Space (coordinate system, length;
  scalar)
 Time (definition of event; scalar)

 Mass (resistance to motion,
  attraction to the earth; scalar)
 Force (direct contact, action at-a-
  distance; vector)
Idealizations in
Mechanics
   The mass point or particle
    (position and mass)
   The rigid body (position, size
    and mass)
   The deformable body (position,
    size, mass and deformability)
Fundamental Principles
   Parallelogram law for addition of
    forces (and vectors)
Fundamental Principles
   Transmissibility (bodies must be
    rigid!!!)


                 =
      pushing     =    pulling
Fundamental Principles
   Newton’s first law

“Every body continues in a state
 of rest, or of uniform motion in a
 right line, unless it is compelled
 to change that state by forces
 impressed on it.”
Fundamental Principles
   Newton’s second law

“The change of motion is
 proportional to the motive force
 impressed; and is made in a
 direction of the right line in
 which the force is impressed.”
Fundamental Principles
   Newton’s third law

“To every action there is always
 opposed an equal reaction: or,
 the mutual actions of two bodies
 upon each other are always
 equal, and directed to contrary
 parts.”
Fundamental Principles
   Newton’s law of gravitation

“Two particles will be attracted
 toward each other along their
 connecting line with a force
 whose magnitude is given by:
                m1m2
             FG 2
                 r
“The weight of a body”
   GM               GM m  gm
F        2
             m    W  2 
   (R  h)         R 

    m
            R+h
M       R
Systems of Units
   International (mks)
Force is derived unit.    1N1kg1m s2


   American (fps)
Mass is derived unit. 1slug 1lb 1ft s2
                     1lbm 1lb 32.2ft s2

				
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posted:11/3/2011
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