Cases of Position time Graph - Motion in a Straight Line Video Lecture - Class 11

hello friends this video on motion in a
straight line part six is brought to you
by exam feel calm no more fear from
exams please make sure that you have
watched part 1 to part 5 before going
ahead with part 6 now we will look at
interpretation from different position
time graphs that is we will plot
position time graphs for different
scenarios let us take the first scenario
position time graph just work making
things clear this is your time and this
is your position or displacement suppose
you have a graph like this now what does
this graph signify
think over it well this graph say is
that the position of the particle was
this when time verse 0 the position of
the particle remains the same when time
verse 1 it remains the same when time
kept increasing that means with increase
of time the position of the particle
remains the same that means there is no
change in position with time that means
there is no motion that means so this
graph so shows that there is no motion
because there is no change of position
with time time is increasing but
position is not changing so no motion
that means the body is at rest fine ok
now let us look at case 2 here we have a
straight line passing through the origin
where this is my time and this is my
position
now here we have that the position is
increasing with increase in time and it
is a straight line that means position
is increasing with increase in time that
means when the time is one position is
one when time is two the position is two
time is three position is three that
means it is increasing uniformly so in
this case we say that the body is in
uniform motion uniform motion means it
is changing equal distance equal the
change in position with respect to time
is uniform that means in first one hour
it changed its position that is one
again in the next one hour the change in
position was one again in the next one
hour the change in position was one and
so on so the body is changing its
position uniformly with the passage of
time that means the body is in uniform
motion or the uniform motion means the
body is traveling with uniform velocity
why did we talk of velocity because it
is position time graph ad then had this
name a distance time graph we would have
talked of speed so when we have a
straight line we see that the body is
moving with uniform velocity let us look
at case three here also we have a
straight line but the line does not pass
through the origin this is our origin
but the line passes through this point
so time is along x axis position is
along y axis in this case it shows that
the object is at rest from 0 to 1 that
means from 0 to 1 the time kept
increasing but the object there is no
change in position of the object the
object is at zero
that means the object has no motion till
first one hour only after that the
change of position with time kept
increasing uniformly so that means the
body is at rest for first hour after
that uniform motion correct now let us
see K is for his four seems to be a
curve what does this signify observe it
very closely from origin till one we can
see that it is nothing but a straight
line that means the object's position is
changing uniformly with time from zero
to one time interval it is uniform
motion as we already discussed now from
one till this point now let us suppose
this point is somewhere around four so
from one till four it is a curve however
it is increasing but it is curved that
means with the increasing time the
position is also increasing but the
increase is not uniform I mean it is not
increasing in equal intervals that means
after that so 1 onwards it is non
uniform motion now if we see the last
part somewhere around this part it is
again a straight line that means beyond
this say let us suppose maybe around
this point the value of x will be
somewhere around 7 or above let us say
towards the end it is not moving that
means there is no change in position
with time that means the body is at rest
so what did we see in this figure
initially it moved initially it moved
with uniform motion then the motion was
non-uniform and then finally the object
has no motion that is it is at rest or
no motion so I hope now it is clear to
you how to plot the position time graphs
and how to interpret the value of
velocity from the slope of position time
graph and what are the different
physique types of position time graph
from which you can interpret the motion
of the object thank you visit exam
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