Interpretation of Distance-Time Graphs Video Lecture - Class 7

hello friends this video on motion and
time part 8 is brought to you by its
vampire calm
no more fear from exam so now that we
have got a good idea about motion let us
talk about these two types of motion
uniform and non-uniform motion so what
is uniform motion uniform means
something which happens smoothly
something which happens you know like
very regularly so that is uniform so a
body is said to be in uniform motion if
it covers equal distances in equal
intervals of time so what it means is
let's say this is a car and this car is
moving uniformly so if I say uniformly
that means for every interval of time it
is covering the same distance that is
for example it started from point A and
it reached point B right so that's how
the cart moved here now what I mean to
say is let's suppose that in the first
time interval say in a time period of 1
minute it covered a distance of say
let's say 500 meters in the next 1
minute it again covers 500 meters again
in the next one minute
it covers 500 meters so if it covers
same distance in a equal interval of
time then we say that the motion is
uniform whereas when we talk about non
uniform motion that means it covers
unequal distances in equal intervals of
time so as you can see in this picture
so here you have different wavelets so
all of these are moving with different
speeds so sometimes it covers whole
distances sometimes it covers less
distances as you can see here the orange
colored car so it initially was like
moving very slowly so just look at this
look at the green car and the red car
they are like moving gradually so they
are moving
at the same speed but if you look at the
orange car what do you observe you
observe that initially the car is moving
slow and then suddenly it starts moving
fast so that means it is not covering
equal distances in equal intervals of
time so this tells you the difference
between uniform and non-uniform motion
so in case of non-uniform motion baby in
the first say one minute it travels 200
meters it can happen that in the next 1
minute
it travels 500 meters again it might
happen that in the next 1 minute
it travels 10 meters so this is an
example of non-uniform motion now
looking at the distance time graphs you
can interpret a lot of things now that
you know what is uniform motion what is
non-uniform motion so we know a lot of
things so let us look at different
distance tile graphs and let's see what
kind of information do we get from them
so say this is the distance on the y
axis this is time on the x axis so if
you have a graph like this what does
this mean this is the line of the graph
that means the time is increasing as
time increases the distance covered
remains the same so that means the
object is not covering any distance with
time that means the object is not moving
at all the object is located at the same
position so that is why the distance
covered is same it is it is at 3 so even
though the time is increasing so this
would mean that the body is at rest so
the body is not moving body is not in
motion so looking at the graph itself we
could interpret that the body is not
moving let's look at another case so
here you see a different graph so here
you have a graph like this where you see
the time is increasing so each point on
the graph if you try to look at each of
these points they will correspond to a
point on the x-axis and a point on the
y-axis
and as time is increasing as the value
of time is increasing from 1 to 2 from 2
to 3 similarly the distance covered is
also increasing from 1 to 2 and 2 to 3
so as time is increasing distance is
also increasing in this case and also
here you see that in the first interval
of time that is in one unit of time so
if we say that this is an hour so in the
first 1 hour it traveled 1 kilometer in
the second 1 hour
it traveled again 1 kilometer in the 3rd
1 hour it travelled again 1 kilometer so
it is covering equal distances in equal
intervals of time so that means the body
is in uniform motion so just looking at
the graph we could say that the body is
in uniform motion so I hope you
understood this so this is the first 1
hour this is the second one out so how
much distance is traveled in this second
1 hour
so how will you calculate that so till 2
hours the total distance traveled is 2
kilometer but in the first 1 hour 1
kilometer is traveled so 2 minus 1 1 so
1 kilometer is traveled in the second
interval and so on let's look at case 3
here we have a graph which is similar to
the case 2 but here it is not passing
through the origin so what does that
show that shows that initially the graph
is like this so that means initially as
time was increasing the distance was not
increasing and only after that distance
started increasing so initially the
object was at rest so this portion till
this much time the object was at rest
and only after this the object started
moving and when it started moving it
started moving uniformly so whenever you
have a straight line like this it shows
uniform motion but initially the object
was at rest case 4
so here you have a curvy line so it
shows that yes if you consider any point
on the curve you see that time is
increasing at each of these points so as
time is increasing what you see the
distance is also increasing which shows
that the body is moving of course but it
is not moving uniformly so in the first
1 hour
it travelled this much distance in the
second 1 hour how much distance it
traveled it travelled this much distance
which is more in the third 1 hour that
is maybe here so you see again it
traveled less so the distance traveled
in each interval of time is different
so this graph portrays non uniform
motion so therefore whenever an object
is in uniform motion the graph would be
a straight line if the graph is a curved
line that means it is non uniform motion
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