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Engineering Mechanics
is the single most
important subject
for all engineers.
Everything you learn
here will be the
foundation for many
other design and
analysis classes you
will be taking.
So it is very important that
you understand all
of the major concepts
in Mechanics. Some of
the concepts are not intuitive.
It is more intuitive
for lot of people to
think of earth as a
flat place and that
sun rotates around it,
but we know now this
is not the case.
Earth is round and
we orbit the sun. If
things were always
obvious and intuitive,
Newton's law would
have developed
hundreds of years before
it was. So keep in
mind understanding
these concepts may
require a little bit of imagination,
visualization,
and experimentation.
Engineering Mechanics
deals with the study
of the response of
bodies under the action
of forces.
As engineers we design
and build things,
and we have to make
sure that things we
design perform exactly
the way they are
supposed to. An automobile,
an airplane, your
home, a bridge, an elevator,
and a cell phone,
are all things made
possible by engineering
design.
As you can see, failure of
these systems is not
only expensive, but may
also be catastrophic.
Engineering mechanics
is the subject that
helps us to study how
these systems behave
when forces are applied.
For convenience we
divide mechanics into
three parts: Statics,
Dynamics, and Mechanics
of Materials.
In statics, we look
at how a system
performs under the
actions of balanced
forces. In other words
we study systems
when they are in equilibrium.
Examples of systems
we study under the
condition of equilibrium
include everything
from simple systems
like tables and chairs,
to more complex
systems like massive
bridges and skyscrapers.
In dynamics, we look
at bodies in motion
under the actions of
unbalanced forces. This
means we are going
to deal with systems
that accelerate.
When we go out for a
run from standing, we
apply forces to our
body so it can accelerate.
When we start driving,
we start accelerating
our car. When a plane
takes off, or lands, it
is subjected to acceleration.
We study all of
this in this course.
Dynamics has two distinct
parts - kinematics
and kinetics.
Kinematics focuses on
the study of motion.
Let us start our discussion
with that. When we say
the word motion
a few things come to
our mind. Motion means
movement from one
location to another.
For example,
I am taking a step and
thus I moved from
one point to another
point. This movement
causes change in position,
and covers a certain distance.
We will call this
displacement.
It is obvious that it
also takes a certain
amount time to complete
this action.
The time it has taken to
cover this distance
is speed. Speed is a
term that we use in
our life everyday.
For example, I am
driving my car and I
am going sixty miles an
hour. This is speed.
If we can also include
direction with
speed, such as I am
going sixty miles an hour
north, then we will use
the term velocity
instead of speed. Speed
is just a number, or
also known as "magnitude".
But the term
velocity includes
the direction of
movement. Velocity is a vector.
The velocity also can
change. It changes as
the body goes faster,
slows down, or changes in
direction.
The change in velocity
is acceleration.
In Kinematics we are
going to deal with
displacement
velocity, acceleration,
and time.
These are also
called kinematic quantities.
In a nutshell, kinematics
will help us to
find answers to the
following questions:
How far? How fast?
How much faster?
And how long?
How far deals with
the displacement.
How fast deals with the velocity.
How much faster deals
with acceleration.
How long deals with
time.
So in this session we will study
the relationship
involving displacement,
velocity, acceleration,
and time. Let us now
develop a few simple
equations involving
these parameters.
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