9th Class Physics Chapter 2 Short Questions with Answers Solved

Question: 1

Define Motion.

Answer: 1

1-120

A body is said to be in motion, if it changes its position with respect to its surroundings. Example: A train is changing its position with respect of platform so it is in motion .

Question: 2

What is rotatory motion? Give example.

Answer: 2

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The spinning motion of a body about its axis is called rotatory motion. Example: The Motion of wheel about its axis. Earth revolves around its geographical axis that causes day and night.

Question: 3

What is a vector quantity?

Answer: 3

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Vector quantity described completely by magnitude and direction . Example: Weight, force, momentum etc.

Question: 4

Define Rest.

Answer: 4

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A body is said to be at rest, if it is not changing its position with respect to its surroundings . Example: A tree with respect to a platform is at rest because it does not change it position.

Question: 5

Define circular motion.

Answer: 5

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Motion of a body in a circular path is called circular motion. in circular motion a point around which body moves lies outside the body

Question: 6

Define vibratory motion.

Answer: 6

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To and fro motion of a body about its mean position is known as vibratory motion Example: Pendulum of clock has vibratory motion.

Question: 7

Define speed.

Answer: 7

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Distance moved by an object in unit time is called speed. Formula: its formula is v=s/t its unitis ms-1

Question: 8

Define uniform speed.

Answer: 8

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A body has uniform speed if it covers equal distance in equal intervals of time however the short interval may be .

Question: 9

Define random motion and give example.

Answer: 9

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Random Motion:

The disordered or irregular motion of an object is called random motion for example, the motion of insects and birds.

Question: 10

What is scalar quantity and also give example.

Answer: 10

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A quantity which can be described by its magnitude only is called scalar quantity Example: Distance, work,power etc.

Question: 11

A car starts from rest. Its velocity becomes 20ms-¹ in 8s.

Find the acceleration.

Answer: 11

11-120

Vi = 0ms-¹

Vf= 20ms-¹

t= 8s

a = ?

We know that

a =Vf - Vi/t

putting values, we get

a= 2=-0/8

a=20/8 =2.5

a= 2.5ms-² ans

Question: 12

What is velocity?

Answer: 12

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The rate of change of displacement of a body is known as its velocity . It is a vector quantity . Formula: V= d/t

Question: 13

Define axis:

Answer: 13

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An axis is a line around which a body rotates.

Question: 14

Define variable.

Answer: 14

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The quantities among which the graph is plotted are called variables.

Question: 15

Define acceleration and write its formula.

Answer: 15

15-120

Acceleration:

The rate of change of velocity ofbodyis called acceleration.

Formula:

=Vf-Vi/t

Question: 16

Define acceleration.

Answer: 16

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Rate of change of velocity of a body in caused it acceleration, it is a vector quantity. Formula: a= Vf-Vi/t Unit is ms-2 or Kmh-2

Question: 17

Which of the following can be obtained from speed-time graph of a body

Answer: 17

17-120

Initial speed, Final speed. Distance covered,

Using speed time graph of a body we can find all of above quantitites as distance covered can be find out by the area under line curve and acceleration can be find out by the slope of line.

Question: 18

What do you know about position?

Answer: 18

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Position:

The term position describes the location of a place or a point with respect to some reference point called origin.

Question: 19

Differentiate between distance and displacemnt.

Answer: 19

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1.Distance: Length of path between two points is called distance between those points. 2.Distance is scalar quantity and its symbol is S. 3.Its units is metere.

Question: 20

Define rest and motion.

Answer: 20

20-120

Rest:

A body is said to be at rest if it does not change its position with respect to its surroundings.

Motion:

A body is said to be in motion if it changes its position with respect to its surroundings.

Question: 21

Define uniform velocity:

Answer: 21

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If a body covers equal displacement in equal intervals of time however short the interval may be is known as uniform velocity.

Question: 22

Under what conditions the value of g is positive/negative

Answer: 22

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Positive value When the body is moving vertically downward the value of g is positive

Question: 23

Difference between scalar and vector.

Answer: 23

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Scalar:

1- A scalar quantity is described completely by its magnitude only.

2- Mass, length, time etc are examples of scalars.

Question: 24

What is graph?

Answer: 24

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Graph is a pictorial way of presenting information about relation between various quantities.The quantities are dependent and independent.

Question: 25

Sketch a distance-time graph for a body starting from rest. How will you determine speed of body from this graph

Answer: 25

25-120

Distance-time graph for a body starting from rest are of two types.

When speed is constant speed can be determined by slope of line

When speed is variable speed can be find out by slope of tangent line at any point

Question: 26

Does speedometer of a car measure its velocity.

Answer: 26

26-120

No, speedometer only measure the speed of the car, because it can not indicate the direction of motion of the car.

Question: 27

Convert 50kmh-¹ speed of a body into ms-¹

Answer: 27

27-120

Speed of the body= 50kmh-¹

50 x 1000/3600 ms-¹

Question: 28

Define Brownian motion.

Answer: 28

28-120

Random motion of gas molecules is called brownian motion.

Question: 29

What is the equation of motion

Answer: 29

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Equation of Motion:

Equations of motion for uniformly acceleratedmotion are

Vf= Vi +at

S= Vit +1/2at²

2aS =Vf²-Vi²

Question: 30

Can a body moving at a constant speed have acceleration?

Answer: 30

30-120

Yes, When a body move along circular path with constant speed it has acceleration due to centripetal force

Question: 31

Differentiate between Rest and motion.

Answer: 31

31-120

Rest: A body is said to be at rest , if it is not changing its position with respect to its surroundings. Examples: A wall ii. A chair

Question: 32

What are the points to be kept in mind when bodies are moving freely under gravity

Answer: 32

32-120

While using equatins of motion for bodies falling freely, it should be kept in mind that

Question: 33

Define circular motion

Answer: 33

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Circular Motion: Motion of a body in a circular path is called circular motion. In circular motion a point around which body moves lies outside the body.

Question: 34

Differentiate between distance and displacement.

Answer: 34

34-120

Distance:

Length of a path between two points is called the distance between those points.

Question: 35

When doses the acceleration of a body is positive and negative.

Answer: 35

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When the velocity of a moving body is increasing with time its acceleration is positive When the velocity of a moving body is decreasing with time its acceleration is taken as negative it is also called retardation or deceleration,

Question: 36

Write types of motion types of Motion:

Answer: 36

36-120

There are three types of motion.

1- Translatory motion

2- Rotatory motion

3- Vibratory motion.

Question: 37

Differentiate between translator motion and circular motion.

Answer: 37

37-120

Translators motion: In translational motion, a body moves along a line without any rotation. the lines may be straight or curved. Example. i. Motion of the side in ferris wheel. ii. Motion of a car along a straight line.

Question: 38

Define uniform acceleration.

Answer: 38

38-120

A body as uniform acceleration if it has equal changes in velocity in equal intervals of time however short interval may be.

Question: 39

Define vibratory motion and give example.

Answer: 39

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Vibratory Motion:

To and fro motion of a body aboutsits mean position is known as vibratory motion.

Example:

Motion of a see-saw.

Question: 40

Why vector quantities cannot be added and subtracted like scalar quantities.

Answer: 40

40-120

Vectors cannot be added like scalars because in scalars we have only magnitude so scalars are added by ordinary algebra while in vectors direction is also important so, they can be added using head to tail rule.

Question: 41

Define circular motion . With example

Answer: 41

41-120

Circular Motion:

The motion of a object in a circular path is known as circular motion of ceiling fan.

Question: 42

Define uniform acceleration

Answer: 42

42-120

A body as uniform acceleration if it has equal changes velocity in equal interval of time. however short interval may be

Question: 43

Define kinematics

Answer: 43

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Kinematics:

The study of motion of objects without discussing the cause of motion is called kinematics.

Question: 44

What is meant by positive and negative acceleration?

Answer: 44

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Positive acceleration:

Acceleration of a body is positive if its velocity increases with time.

Question: 45

Define vibratory motion

Answer: 45

45-120

To and Fro motion of a body about its mean position is known as vibratory motion

Question: 46

Define rest

Answer: 46

46-120

A body is said to be at rest, if it is not changing its position with respect to its surroundings.

Question: 47

Define rotatory motion. With example.

Answer: 47

47-120

Rotatory Motion:

The spinning motion of a body about its axis is called rotatory motion.

Examples:

Motion of top, motion of ceiling fan.

Question: 48

How is a vector represented?

Answer: 48

48-120

Graphically a vector can be represented by a line segment with a arrow head which represents its direction and the length of line segment gives its magnitude according to selected scale.

Question: 49

A body is moving with uniform speed

Answer: 49

49-120

Velocity of a body has magnitude as well as direction. For a body to more with uniformvelocity it speeds as well as its direction should remain the same Thus it can only me possible if a body is moving in a straight line with constant speed, then its velocity will also be uniform i.e if a body does not change its direction.

Question: 50

Define vector and write the name of two methods of vector,quantities, representation,

Answer: 50

50-120

Vector:

A vector quantity is described completely by magnitude and direction

There are two methods of vector representation.

1- Symbolic representation

2-Graphical representation

Question: 51

What is rotatory motion

Answer: 51

51-120

The spinning motion of a body about its axis is called rotatory motion

Question: 52

Define gravitationalacceleration .

Answer: 52

52-120

The accelerationof freely falling bodies is called gravitationalacceleration. Its value is 10ms-²

Question: 53

Can a body moving at a constant speed have acceleration

Answer: 53

53-120

No because there is no change in its speed. While change in speed is a necessary condition for acceleration, fso acceleration will be zero But except in a circular path.

Question: 54

Define dependent and independent quantities.

Answer: 54

54-120

The quantitiy which can vary with our wish is called independent quantity

Dependent The quantity whose value according to the changes in independent quantity dependent quantity.

Question: 55

Define position and give exmple.

Answer: 55

55-120

Position means the location of a certain place or object from a reference point

Examples: In figure the point P represents the positive of the body with respect to origin O

Question: 56

How a vector can be represented graphically

Answer: 56

56-120

Graphically a vector can be represented by a line segment with an arrow head.

Example: In figure, a line AB write arrow head on one side. The length of line shows the magnitude of vector and the arrow head shows its direction.

Question: 57

How are vector quantities important to us in our daily life.

Answer: 57

57-120

With the help of vectors we can locate or point out the position of any object Action and reaction forces can also be explain in terms of vectors.

Question: 58

how can we convert 1ms into kmh

Answer: 58

58-120

The given speed in ms is multiplied by 3.6 to get speed in kilometer per hour

Question: 59

Define scalar quantity and also give example

Answer: 59

59-120

A quantity which can be discribed by its magnitude only is called scalar quantity

Question: 60

What is velocity

Answer: 60

60-120

The rate of change of displacement of a body is know as its velocity. it is a vector quantity

Question: 61

Define uniform speed

Answer: 61

61-120

A body has uniform speed if it covers equal distance in equal intevals of time however the short interval may be

Question: 62

Define circular motion. With example.

Answer: 62

62-120

Circular Motion:

The motion of a object in a circularpath is known as circular motion.

Example :

Motion of earth around sun.

Question: 63

Define Brownain motion

Answer: 63

63-120

Define Brownian motion

Question: 64

Define axis.

Answer: 64

64-120

An axis is a line around which a body rotates.

Question: 65

When body are moving in upward direction

Answer: 65

65-120

Final velocity vf of the body will be zero

Gravitational acceleraton will be negative

Question: 66

Define Average Velocity and write its formula.

Answer: 66

66-120

Average Velocity: The change in total is displacement with respect to total time is called average velocity

Average Velocity: Total displacement/total time.

Question: 67

Define variable

Answer: 67

67-120

The quantities among which the graph is plotted are called variables

Question: 68

What is graph

Answer: 68

68-120

Graph is pictorial way of presenting information about relation between various quantities The quantities re dependent and independent

Question: 69

What would be shape of speed-time graph of a body moving with variable speed.

Answer: 69

69-120

Shape of a speed-time graph of an object moving with variable speed will always be a curve. It would never be a straight line.

Question: 70

Write equations of motion

Answer: 70

70-120

Equations of motion due to gravity are as

Question: 71

Define terminal velocity

Answer: 71

71-120

When an object moves vertically downward nd it attains uniform velocity. Then its uniform velocity is called terminal velocity.

Question: 72

How can we convert kmh into ms

Answer: 72

72-120

The given speed in kmh is divided by 3.6 to the speed in ms

Question: 73

What is LIDAR

Answer: 73

73-120

A motorway speed camera. A LIDAR gun is light detection and ranging speed gun It uses the time taken by laser pulse to make a series of measurements of a vehicle distance from the gun The data is then used to calculate the vehicle's speed

Question: 74

In the absence of air resistance during the free fall motion, which body ground first light or heavy

Answer: 74

74-120

As the gravitational acceleration is independent of the mass of the body so if we neglect air resistance all the bodies fall to the ground at the same time.

Question: 75

Sketch a speed time graph of on object moving with uniform

Answer: 75

75-120

If a body is moving uniform changing speed its speed time graph is straight line

Question: 76

How vector quantities are representation

Answer: 76

76-120

Graphically a vector can be represented by a line segment with an arrow head which represents its direction and the length of line segment gives its magnitude according to selected scale. AB is length of vector V and its diectioin is from A to B

Question: 77

Why does the velocity of a thrown up body become zero at the highest point

Answer: 77

77-120

When a body is thrown vertically upward it moves under gravity against the force of attraction of Earth So after every second the velocity of the body decreases by 9.8 and ultimately becomes zero at the highest point That is why the velocity of a body becomes zero at the highest point

Question: 78

How do riders in a ferris wheel possess translatory motion but not rotatory motion

Answer: 78

78-120

Riders of Ferris wheel possess translatory motion because they move in circular track without spinning while the itself motion of Ferris wheel is rotatory.

Question: 79

When bodies are moving in downward direction

Answer: 79

79-120

Initial velocity v of the freely faling body will be zero

Gravitational acceleration will be positive.

Question: 80

Define Motion also write its types.

Answer: 80

80-120

Motion: A body is said to be motion, if it changes its postion with respect to tis surrounding.

Example: Moving car on road

Question: 81

Define gravitational acceleration

Answer: 81

81-120

The acceleration of a body when it moves vertically upward or downward freely is called gravitational acceleration

It is denoted by g

Its magnitude is 10ms at earth

Question: 82

How ms2 converted into kmh2

Answer: 82

82-120

To convert acceleration form ms to kmh we multiply it with 12960

Question: 83

Who noticed about all freely falling objects fall with same acceleration

Answer: 83

83-120

Galileo was the first scientist who noticed about all freely falling objects fall with same acceleration g

Question: 84

Give an example of a body that is at rest and is in motion at the same time.

Answer: 84

84-120

A passenger sitting in a moving bus is at rest because he/she is not changing his/her position with respect to other passenger or objects in the bus. But to an observer outside the bus, the passengers and the objects inside the bus are in motion

Question: 85

Differentiate distance and displacement.

Answer: 85

85-120

Distance: Length of a path between two points is called the distance between those points.

It is a scalar quantity.

Distance represented by S

Distance can be find by the formula

In picture dotted line shows distance.

Question: 86

Different between distance and displacement.

Answer: 86

86-120

The difference b/w distance and displacement is following.

Question: 87

Differentiate speed and velocity.

Answer: 87

87-120

Speed Rate of change of distance is called speed.

It is a scalar quantity

Its unit is ms

It is drived by following formula.

Question: 88

Define Kinematic

Answer: 88

88-120

Kinematics: Kinematics is the study of motion of an objects without discussing the casuse of motion.

Question: 89

What is meant by position

Answer: 89

89-120

The term position describe the location of a place or point with respect to some reference point is called origin.

Question: 90

Mention the type of motion in each of the following

Answer: 90

90-120

A ball moving vertically upward: If a ball is moving vertically upward then its motion is linear

Question: 91

Convert 20ms speed in kmh

Answer: 91

91-120

Speed in ms = 20ms

Question: 92

Write types of motion

Answer: 92

92-120

There are three types of motion.

Translatory motion linear random and circular motion

Rotatory motion, Vibratory motion.

Question: 93

Wha is significance of graph in daily life

Answer: 93

93-120

A graph may also be used in everyday life such as to show year wise growth decline of export month-wise rain fall, a patients temperature record or runs per over scored by a team.

Question: 94

A sprin'er complete its 100m race 12s, Find its average speed

Answer: 94

94-120

Total distance=100m

Average speed= Displacement/Time Taken

Question: 95

Does speedometer of a car measure its velocity

Answer: 95

95-120

No speedometer only measures the speed of the car because it can indicate the direction of motion of the car.

Question: 96

Writer four examples of vectors.

Answer: 96

96-120

Scalar: The quantities which are described completely by its magnitude only is called scalar quantities.

Examples: Mass, length, time speed and volume.

Question: 97

Define speed and write its unit.

Answer: 97

97-120

Speed The distance covered by an object in unit time is called its speed Speed is scalar quantity

Question: 98

Cheeta can run at a speed of 70 kmh convert this speed

Answer: 98

98-120

speed of Cheetah =v= 70kmh

Question: 99

Define velocity and rite its equation

Answer: 99

99-120

Velocity: The rate of change of displacement is called velocity

Question: 100

Define two types of motion.

Answer: 100

100-120

Linear Motion: Straight line motion of a body is know as its linear motion.

Example Car moving on straight line.

Question: 101

Write down the formula and unit to find Acceleration.

Answer: 101

101-120

Formula: Acceleration can be found out by given formula

Acceleration = Change in velocity/time taken

Question: 102

A sprinter completes its 100 meter race in 12 Find his average speed

Answer: 102

102-120

Total distance = 100m

Total time taken = 12s

Average speed= Total distence covered/Total time taken

Question: 103

How are vector quantities important to use in our daily

Answer: 103

103-120

Vector quantities are important to us in our daily life in engineering, building and drawing diffferent techniques. If we want find direction of moving object then we can do with help of vector quantities.

Question: 104

When a body falls freely, which quantity remains the same and which increases

Answer: 104

104-120

During the free fall motion, acceleration is independent of the mass of the body remains the same throughout the motion and velocity of the body increases continuously.

Question: 105

Define uniform velocity

Answer: 105

105-120

A body has uniform speed if it covers equal distance in equal intervals of time however short to interval may be.

Question: 106

A player coves 80m distance in 10 second

Answer: 106

106-120

Required: Average speed =vav

Question: 107

Differentiate between rest and motion

Answer: 107

107-120

Rest A body is said to be at rest, if is not changing its position with respect to its surroundings.

A wall, A chair

Question: 108

A train moves with a uniform velocity of 36 kmh for 10s

Answer: 108

108-120

velocity of train = v = 36kmh

Question: 109

Differentiate between variable and uniform speed

Answer: 109

109-120

Variable speed: A body has variable speed if does not cover equal distance in equal intervals of time. however short the interval may be.

Question: 110

What is retardation

Answer: 110

110-120

The acceleration of a body whose velocity decreases is called retardation It is also called negative acceleration of body

Question: 111

What is Lidar gun

Answer: 111

111-120

A Lidar gun is light detection and ranging speed gun It uses the time taken by laser pulse to make a series of measurements of a vehicles distance from the gun. The data is then used to calculate the vehicles speed

Question: 112

Differentiate between translator motion and circular motion

Answer: 112

112-120

In translational motion, a body moves along a line without any rotation., The lines may be straight or curved

Example Motion of the sides in Ferris wheel.

Motion of a car long a straight line.

Question: 113

Why vector quantities cannot be added and subtracted like scalar quantities

Answer: 113

113-120

The quantities having direction cannot be added and subtracted like scalar quantities because scalar quantities have no any direction but the vector quantities have direction.

Question: 114

Define gravitational acceleration.

Answer: 114

114-120

The acceleration of a freely falling bodies is cled gravitational acceleration. It is denoted by g Its value is

Question: 115

What is difference between positive acceleration and negative acceleration

Answer: 115

115-120

Negative acceleration: Acceleration of body is negative if velocity of the body decreases with time The negative acceleration is also called deceleration or retardation.

When moving bodies stops it gives retardation

The direction of negative acceleration is opposite to the direction in which the body in moving.

Question: 116

What would be the shape of a speed time graph of a body moving with variable speed.

Answer: 116

116-120

When a body is moving with variable speed the shape of its speed time graph is not a straight line It is always a curved path.

Question: 117

How is a vector represented

Answer: 117

117-120

There are two methods to represent a vector

Question: 118

Define uniform speed and uniform velocity.

Answer: 118

118-120

Uniform speed: A body has uniform speed if it covers equal distance in equal intervals of time however short the interval may be

Question: 119

Define terminal velocity.

Answer: 119

119-120

Terminal velocity: The uniform velocity of free falling objects attains is called terminal velocity.

Example A paratrooper attains a uniform velocity called terminal velocity with which comes to ground

Question: 120

Write three equations of motion for bodies moving under gravity.

Answer: 120

120-120

Following are the equations of motion under gravitation.

First equation of motion vf= vi+gt

Physics Chapters

9th Class Chapter 2 Physics Short Questions

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