MOTION
LEARNING OBJECTIVES
After a study of the chapter, the
learner will be able to
• Distinguish between uniform and
non-uniform motion using the graphical method.
• Calculate numerically value the
displacement, velocity, or acceleration using an equation of motion. Appreciate
that uniform circular motion is accelerated motion.
• Identify the given physical quantities
as vector or scalar.
• Explain that motion is relative in
nature.
Motion forms an integral
part of our life. All microscopic and macroscopic objects in-universe show some
kind of movement. All of the objects such as planets, moons, etc. It also exhibits
motion.
All
these examples can be clearly understood and discuss if we can describe motion,
its property, and other related aspects such as displacement speed, etc. In
this chapter, we shall study the motion and its representation.
Rest:-
If the position of an object does not changes as
the time passes, it is said to be at rest.
Motion:-
If the position of an object changes as the
time passes it is said to be in motion.
Reference point-
The point from
where the object starts its motion is said to be its reference point.
Scalar quantity
The quantity
having only the magnitude it is said to be scalar quantity full stop for
example mass, speed, distance, etc.
Vector quantity:-
The quantity
having magnitude as well as direction is a call vector quantity. for example
weight, velocity, displacement, etc.
Distance:-
Distance
traveled by an object in any direction is called distance.
It is a scalar
quantity its unit is km or m.
Displacement:-
The shortest the straight-line path traveled by an object in a given direction is called
displacement. It is a vector quantity its unit is km or m.
Diagram 1
Difference
between distance and displacement
Distance
Displacement
1.
The path traveled by an object in a given direction called distance.
2.
It is a scalar quantity.
3.
This is always positive. It cannot be zero or
negative.
4.
For example, an object travels 5 kilometers in any direction.
1.
The shortest straight-line path
traveled by an object in a given direction called displacement.
2.
It is a vector quantity.
3.
Displacement can be positive or
negative.
4.
For example and object travel 5 kilometer
in the north direction.
Uniform motion
A body said to
be in uniform motion when it travels the equal distance in equal interval of time.
Diagram 2
Non-uniform motion
A body said to
be in non-uniform motion when it travels the unequal distance in equal interval of
time.
Diagram 3
Note:-
1. If the distance-time graph is
a straight line, the motion will be uniform.
2. The distance-time graph is curved
the line then the motion will be non-uniform.
Speed:-
Speed of a body
is the distance traveled by it in unit time .
Formula Speed =distance / time
The units of speed are km / h or m/s.
For example, if a bus cover 30
a kilometer into hours then the speed of the bus is given by distance/ time=30 / 2
=15 km / h.
·
Speed
of any vehicle is measured by the device called speedometer.
·
Speed
is a scalar quantity.
Average speed
It is defined as
the total distance traveled divided by the total time taken to cover the
distance.
For example a
the car travels a distance of 100 km in 4 hours then its average speed can be found
as 100 / 4 =25 km / h.
Uniform speed or constant speed
A body said to
be in uniform speed if it covers equal distance in equal interval of time.
Velocity
It is defined as the displacement
traveled by any vehicle per unit time
in a given direction.
Or
It is defined as
displacement of a vehicle per unit time.
Formula Velocity=
displacement / time taken.
·
It
has a unit meter or kilometer.
·
It
is a vector quantity.
Uniform velocity
A body said to
be in uniform velocity if it travels in a particular direction in a straight line
on move over equal distance in equal interval of time.
Note:-
1.
Velocity
of a body can be changed in two ways:-
· But changing the
speed of the body.
· By keeping speed
constant but changing the direction.
2.
Speed
and velocity is not always equal in magnitude.
3.
If
object travel in a straight line then speed is equal to velocity.
For example, Sohan travels a distance of 30 kilometers from home to school in 2 hours. after some time, Sohan
come back to home in 2 hours, then
distance traveled by the Sohan is 60 kilometers but the displacement travel by
the Sohan is zero, then the speed of the Sohan=60 / 4=15km/h.
But, the velocity of the Sohan=0/4=0 km/h.
Because Sohan
come back to his home so the distance between the starting point and ending point
will be zero so its velocity will be zero.
Difference between speed and
velocity
Speed
Velocity
1.
It is defined as the distance covered by the body in a given interval time.
2.
It is a scalar quantity.
3.
Speed for the body can never be zero, if
it covers some distance.
4.
For example, the speed of the vehicle is given
by 25 km/h.
5.
Formula
Speed=distance/time.
1.
It is defined as displacement covered
by the body in a given interval time.
2.
It is a vector quantity.
3.
Velocity for the body can be zero if its an initial and final point of destination is same.
4.
For example, the speed of a vehicle is
given by 25 km/h in north direction.
5.
Formula
Velocity=displacement / time.
Acceleration:-
It is defined as
change in velocity of a body in a given interval of time or in per unit time.
diagram 1 as
shown above, an object is moving in a straight line and you is its initial
velocity at point a we become the final velocity V within time so, acceleration
given by
acceleration = final velocity - initial
velocity
time taken
a = v-u
t
Types
of acceleration
1.
uniform
acceleration
2.
non
uniform acceleration
Uniform acceleration ( Definition)
when there is
equal change in velocity of a body in equal interval of time .
diagram 2
Non uniform acceleration (definition)
when there is an unequal change in
velocity of a body in an equal interval of time or an equal change in velocity
in equal interval of time then object should have non uniform acceleration .
diagram 3
Cases in acceleration
There are three cases and acceleration given
below-
1.
Positive
acceleration
2.
Negative
acceleration
3.
Zero
acceleration
Positive acceleration
Definition:-
The acceleration said to be positive if there is an increase in velocity of a
body.
a=v-u/t [v>u]. =positive
Negative
acceleration
Definition :-
The acceleration said to be positive if
there is a decrease in velocity of a body.
a=v-u/t [v<u]. = negative
Zero acceleration
Definition:- The acceleration
said to be positive if there is no
change in velocity of a body.
a=v-u/t =0 [v=u].
Graphical representation of motion of an
object
In
2D - graph there are two axis x and y.
We always take time on x- axis and velocity
or displacement or distance on y
axis.
1. D-t graph( distance time graph)
2. V-t graph( velocity time graph)
Uniform circular motion
Definition:- When object
moving in a circle the motion of an object is said to be uniform circular motion.
In circular motion there can
be a constant speed but no constant velocity because there is only
change in direction at each point.
Speed=Circumference
of a circle / time taken
Speed = 2Ï€r / t
MOTION
LEARNING OBJECTIVES
After a study of the chapter, the
learner will be able to
• Distinguish between uniform and
non-uniform motion using the graphical method.
• Calculate numerically value the
displacement, velocity, or acceleration using an equation of motion. Appreciate
that uniform circular motion is accelerated motion.
• Identify the given physical quantities
as vector or scalar.
• Explain that motion is relative in
nature.
Motion forms an integral
part of our life. All microscopic and macroscopic objects in-universe show some
kind of movement. All of the objects such as planets, moons, etc. It also exhibits
motion.
All
these examples can be clearly understood and discuss if we can describe motion,
its property, and other related aspects such as displacement speed, etc. In
this chapter, we shall study the motion and its representation.
Rest:-
If the position of an object does not changes as
the time passes, it is said to be at rest.
Motion:-
If the position of an object changes as the
time passes it is said to be in motion.
Reference point-
The point from
where the object starts its motion is said to be its reference point.
Scalar quantity
The quantity
having only the magnitude it is said to be scalar quantity full stop for
example mass, speed, distance, etc.
Vector quantity:-
The quantity
having magnitude as well as direction is a call vector quantity. for example
weight, velocity, displacement, etc.
Distance:-
Distance
traveled by an object in any direction is called distance.
It is a scalar
quantity its unit is km or m.
Displacement:-
The shortest the straight-line path traveled by an object in a given direction is called
displacement. It is a vector quantity its unit is km or m.
Diagram 1
Difference
between distance and displacement
|
Distance
|
Displacement
|
|
1.
The path traveled by an object in a given direction called distance.
2.
It is a scalar quantity.
3.
This is always positive. It cannot be zero or
negative.
4.
For example, an object travels 5 kilometers in any direction.
|
1.
The shortest straight-line path
traveled by an object in a given direction called displacement.
2.
It is a vector quantity.
3.
Displacement can be positive or
negative.
4.
For example and object travel 5 kilometer
in the north direction.
|
Uniform motion
A body said to
be in uniform motion when it travels the equal distance in equal interval of time.
Diagram 2
Non-uniform motion
A body said to
be in non-uniform motion when it travels the unequal distance in equal interval of
time.
Diagram 3
Note:-
1. If the distance-time graph is
a straight line, the motion will be uniform.
2. The distance-time graph is curved
the line then the motion will be non-uniform.
Speed:-
Speed of a body
is the distance traveled by it in unit time .
Formula Speed =distance / time
The units of speed are km / h or m/s.
For example, if a bus cover 30
a kilometer into hours then the speed of the bus is given by distance/ time=30 / 2
=15 km / h.
·
Speed
of any vehicle is measured by the device called speedometer.
·
Speed
is a scalar quantity.
Average speed
It is defined as
the total distance traveled divided by the total time taken to cover the
distance.
For example a
the car travels a distance of 100 km in 4 hours then its average speed can be found
as 100 / 4 =25 km / h.
Uniform speed or constant speed
A body said to
be in uniform speed if it covers equal distance in equal interval of time.
Velocity
It is defined as the displacement
traveled by any vehicle per unit time
in a given direction.
Or
It is defined as
displacement of a vehicle per unit time.
Formula Velocity=
displacement / time taken.
·
It
has a unit meter or kilometer.
·
It
is a vector quantity.
Uniform velocity
A body said to
be in uniform velocity if it travels in a particular direction in a straight line
on move over equal distance in equal interval of time.
Note:-
1.
Velocity
of a body can be changed in two ways:-
· But changing the
speed of the body.
· By keeping speed
constant but changing the direction.
2.
Speed
and velocity is not always equal in magnitude.
3.
If
object travel in a straight line then speed is equal to velocity.
For example, Sohan travels a distance of 30 kilometers from home to school in 2 hours. after some time, Sohan
come back to home in 2 hours, then
distance traveled by the Sohan is 60 kilometers but the displacement travel by
the Sohan is zero, then the speed of the Sohan=60 / 4=15km/h.
But, the velocity of the Sohan=0/4=0 km/h.
Because Sohan
come back to his home so the distance between the starting point and ending point
will be zero so its velocity will be zero.
Difference between speed and
velocity
|
Speed
|
Velocity
|
|
1.
It is defined as the distance covered by the body in a given interval time.
2.
It is a scalar quantity.
3.
Speed for the body can never be zero, if
it covers some distance.
4.
For example, the speed of the vehicle is given
by 25 km/h.
5.
Formula
Speed=distance/time.
|
1.
It is defined as displacement covered
by the body in a given interval time.
2.
It is a vector quantity.
3.
Velocity for the body can be zero if its an initial and final point of destination is same.
4.
For example, the speed of a vehicle is
given by 25 km/h in north direction.
5.
Formula
Velocity=displacement / time.
|
Acceleration:-
It is defined as
change in velocity of a body in a given interval of time or in per unit time.
diagram 1 as
shown above, an object is moving in a straight line and you is its initial
velocity at point a we become the final velocity V within time so, acceleration
given by
acceleration = final velocity - initial
velocity
time taken
a = v-u
t
Types
of acceleration
1.
uniform
acceleration
2.
non
uniform acceleration
Uniform acceleration ( Definition)
when there is
equal change in velocity of a body in equal interval of time .
diagram 2
Non uniform acceleration (definition)
when there is an unequal change in
velocity of a body in an equal interval of time or an equal change in velocity
in equal interval of time then object should have non uniform acceleration .
diagram 3
Cases in acceleration
There are three cases and acceleration given
below-
1.
Positive
acceleration
2.
Negative
acceleration
3.
Zero
acceleration
Positive acceleration
Definition:-
The acceleration said to be positive if there is an increase in velocity of a
body.
a=v-u/t [v>u]. =positive
Negative
acceleration
Definition :-
The acceleration said to be positive if
there is a decrease in velocity of a body.
a=v-u/t [v<u]. = negative
Zero acceleration
Definition:- The acceleration
said to be positive if there is no
change in velocity of a body.
a=v-u/t =0 [v=u].
Graphical representation of motion of an
object
In
2D - graph there are two axis x and y.
We always take time on x- axis and velocity
or displacement or distance on y
axis.
1. D-t graph( distance time graph)
2. V-t graph( velocity time graph)
Uniform circular motion
Definition:- When object
moving in a circle the motion of an object is said to be uniform circular motion.
In circular motion there can
be a constant speed but no constant velocity because there is only
change in direction at each point.
Speed=Circumference
of a circle / time taken
Speed = 2Ï€r / t
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