Simple Harmonic motion - Oscillations Video Lecture - Class 11

hello friends this video on oscillations
part 5 is brought to you by exam feel
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before going ahead with part 5 let us
now study what is simple harmonic motion
as I already told simple harmonic motion
is also an oscillating motion it is
basically the simplest form of
oscillatory motion so how do we know
that a particular oscillatory motion is
simple harmonic if we again take the
example of the simple pendulum or that
mass connected to the string we say that
a motion is simple harmonic which is
often known as SH M that a simple
harmonic motion when the force on the
oscillating body is directly
proportional to its displacement from
the mean position at the very beginning
of this chapter I explained you what
this mean position or equilibrium
position of this particular mass so
there is a force which always acts on
this oscillating object which tries to
bring this object to its mean position
so if you leave this object to itself it
will swing for some time and then
finally it will come back to rest at its
mean position so when this force which
acts on this oscillating body is
directly proportional to the
displacement then that kind of motion is
known as ascension that is this object
for example you consider this object so
this mass is getting displaced from this
position to this position right and this
is its mean position so the force which
is acting on this particular mask will
always try to bring it back to its mean
position that is the equilibrium
position
now and this force is proportional to
the displacement that is the amount of
travel which it is going through till
its extreme end it is proportional to
that displacement so when force is
proportional to displacement then we say
that the motion is simple harmonic now
at any point in during this motion this
force is directed towards the mean
position right so that means the force
this force will always try that the
object goes back to its mean position
now how do we denote or how do we
represent displacement in case of simple
harmonic motion I have already told you
how is displacement represented in case
of any oscillatory motion in general now
let us look at this case of simple
harmonic motion let us suppose this is
the mean position of any oscillating
object so how does the motion takes
place the object goes to this extreme
and it again comes back and goes to this
extreme end so these two ends are often
referred to as extreme positions so
these are the two extreme positions and
this is the main position right so how
do we denote a displacement in case of
simple harmonic motion it is very
similar to oscillation so here we say
that X of T that is the displacement
which is a function of time that is it
varies with time is equal to e cos Omega
T plus Phi
there also I told you that this was the
same similar form this was of the
similar form because I do it this place
length in case of an oscillation is
always represented by a function which
is periodic with time so therefore there
also we had I had already explained you
why was this taken as a cosine function
because it is periodic with strength now
let us understand God at
of these downs so what is this a this a
is nothing but amplitude of the simple
harmonic motion
what is this Omega T plus Phi Omega T
plus Phi is nothing but phase of a
system now I don't worry about what is
amplitude and want the space in the next
slides I explaining what this amplitude
what those fees and each of these terms
detail right now I am just telling you
what and each of what does each of these
terms are depressant now what is Omega
Omega is nothing but angular frequency
that you already know and what is phi
phi is phase constant so these are so
these are three new terms which we are
going across know when is amplitude when
as phase and the other one is phase
constant so now in our next slides we
will talk about each of them thank you
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