welcome to the very first episode of
dimension analysis
dimensional analysis is one of the very
very important tool or concept in
physics it's really really important
before starting the advanced physics or
mechanics or any part, you know, so before
learning dimensional analysis I want to
take you to two physical quantities. You
know physical quantities means like a
length, mass, you know, temperature or you
say velocity acceleration current you
know these all are physical quantities
and you know in our universe generally
while studying the total universe you
know in physics we divide those all
physical quantities into two section
first one is primary primary physical
quantities alright or we say some time
fundamental physical quantities also
that's more used you know this is more
commonly used fundamental quantities, all right ? Fundamental physical quantities
that is more better the same fundamental
physical quantities and another is
second way. Secondary physical
quantities or we say derived physical
quantities while learning SI unit you
know International System of Units you
must have learned the two types of the
units fundamental units and secondary
units there also you know that is
determined based completely based on
that fundamental physical quantities and
secondary or direct physical quantities
so first we should learn what are the
fundamental physical quantities. Let me
tell you
understanding dimensional license is
completely based on the fundamental
physical quantities. So now first
fundamental physical quantities we have
learned MASS alright, second we had
learned LENGTH and then we have learned
TIME, you know these fundamental
quantities do not depends on any other
things or any other factors. Another one
is electric CURRENT, fifth one is
INTENSITY OF LIGHT of light. Sixth one is
TEMPERATURE and seventh one the last one
amount of substance.
Amount of substance and the derived
quantities are those quantities which
are made with  these seven
fundamental quantities maybe one maybe
two maybe three or maybe all you know
any. It may be you know simply I
mean to say those quantities those
physical quantities which are made with
these you know let's say let's say I'm
talking about this speed you know speed
ease are derived physical quantities or
secondary physical quantities because
speed means distance means distance
travel in such an interval of time all
right so what is distance what is
distance distance is a length and time
is time so I can say that speed is made
with two things two fundamental things.
That is a length and time so these two
fundamental quantities length and time
makes speed so I can say that speed is
derived from length and time so that's
why that's why you know those quantity
which are made with those these these
fundamental quantities are categorized as derived physical quantities.
Similarly if you if you take
an example of let's say force then force
is what mass times acceleration all right
mass is itself the fundamental
quantities and acceleration is again a
velocity you know velocity divided by
time. all right, times again mass and
again velocity is what this is mass and
again velocity is what it's a distance
you know or better you say displacement
displacement divided by time and
initially there was one more time so
time square so see here mass distance
time these all are what this all are
these quantities you know mass distance
means length time is here so these
quantities are called derived quantities
as they are formed from these
fundamental quantities and my dear
friend this fundamental quantities are
represented like my mass is represented
by Capital m and we closed inside the
the big bracket or what do you say
square brackets all right inside this we
also put this length we represent by L
and we capital L and we keep it inside
that square bracket simply time like
this electric current is measured in
amperes, so we do like this. Intensity of
light candelas CD all right and
temperature Kelvin, all right, an amount
of substance that's [Mol]. Well so like
this also we represent these fundamental
quantities okay so now the things comes
what is dimension you know so dimension
whenever I'm saying then you have to
understand anybody say not me only
anybody saying diamonds and then you
have to understand that it's the powers
or better you say exponents you know
exponents raised to the base quantities
you know base quantities of a unit
quantities of unit, okay ? Let's say  I'm talking about let's say speed
okay so speed is as I told you it's
length divided by time how much length
or how much distance I am traveling in
certain interval of time that's my speed
so same thing can be written as length
times time to the power minus-1 all
right and as I told you length is
represented by capital L and then and
then inside the bracket and time we
represent by capital T inside the square
bracket and power minus 1 so what I can
say that it's L t minus 1 and both
inside the square bracket and if I'm
including here the mass also then mass
has power 0
all right L t minus 1 ok so here M is
having power 0 l is having power 1 and T
is having power minus 1 so dimensions of
speed is zero in mass one in length and
minus 1 in time so dimension means the
powers or exponents raised to the base
quantities of unit of a speed speed unit
unit is what you know if you go to the
further like in a unit way also if you
go then length
Unity's meter and times unit is second
you know so it's it's meter per second
all right so the powers or exponents
you know powers are experience raised to
the base quantities you know the base
quantities of unit so unit is meter per
second meter means representing length
length has how much power one you know
see here and time has how much power
minus one see here so these 1 and minus
1 are the dimension of dimension of
off-speed all right plus one dimension
in length and minus one dimension in
time and zero dimension in mass so
that's that's dimension of a speed and
when we we are going to discuss about
dimension then one thing always keep in
mind that we're not going to talk about
the magnitude
alright magnitude is not considered it's
it's the physical quantities here
whenever we discuss about dimension it's
solely depend on the quality all right
whether I'm saying let's say length or
I'm saying brave or I'm saying height or
I'm saying distance or I'm saying
displacement whatever I'm saying you
know don't go to the magnitude if you if
you come to the quality then all they
means that the same dimension you know
same same units if you go they all means
length you know they all means length
with power one alright so so these all
have the dimension one in length
all right wrist rest of this all is zero
okay so so we we focus on quality rather
than quantity right we we don't consider
magnitude keep in mind whenever we study
dimension and now wrist studies will be
talking in the next view there will
learn about the damage sir formula you
know dimensional some quantities
equations those all things we can
discuss all right I'll see you in the
next video bye-bye
