 # Class 9 Physics Chapter 6

Updated: 21 Oct 2023

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Class 9 Physics Chapter 6 is about “Work and Energy“. This article includes topics such as Work, Energy and its Forms, Kinds of Energy (Kinetic Energy, Potential Energy), Energy and its forms, Energy Conversion and Conservation (A Diver on a Spring Board, Generation of Electricity, Pole Vault), Mass Energy Equivalence (Einstein’s Mass Energy Equation E=mc^2 ), Major Sources of Energy (Fossil Fuels, Bio-mass, Geothermal Energy, Wind Energy, Nuclear Energy, Solar Energy, Hydroelectric Generation), Efficiency and Power.

## Class 9 Physics Chapter 6 Notes

### Work and Energy Notes Class 9 Physics Chapter 6 Notes

### Class 9 Physics Chapter 6 SLO Notes Class 9 Physics Chapter 6 SLO Notes

## Class 9 Physics Chapter 6 MCQs

### Work

1 What is work in scientific terms?
(a) Doing any activity
(b) Applying force without movement
(c) Applying force with movement in the same direction
(d) Applying force with movement in any direction

Applying force with movement in the same direction

2 Product of force and displacement covered in the direction of force is:
(a) Work
(b) Energy
(c) Power
(d) Efficiency

Work

3 When is maximum work considered to be done?
(a) When an object is lifted vertically
(b) When a force is applied at an angle to an object
(c) When there is motion in the opposite direction of the force
(d) When there is motion in the direction of the force

When there is motion in the direction of the force

4 Work is represented by………….
(a) W
(b) E
(c) P
(d) L

W

5 Which formula represents work (W) when force (F) moves an object over a displacement (S) ?
(a) W = F \times S
(b) W = \frac{F}{S}
(c) W = F + S
(d) W = F - S

W = F \times S

6 What will be the magnitude of work if a force of 25 N pulls a stone through a distance of 5 m in its direction:
(a) 25 J
(b) 50 J
(c) 75 J
(d) 125 J

125 J

7 Suppose a person exerts a force of 50 N to push a box a distance of 5 meters . Calculate the work done.
(a) 25 J
(b) 250 J
(c) 50 J
(d) 500 J

250 J

8 A person does 600 joules of work while lifting a box a distance of 3 meters vertically. What is the force exerted by the person?
(a) 25 N
(b) 50 N
(c) 75 N
(d) 200 N

200 N

9 What is the unit of work?
(a) Joule (J)
(b) Newton (N)
(c) Meter (m)
(d) Second (s)

Joule (J)

10 Which unit is equal to kgm^2s^2 in the units given below:
(a) Newton
(b) Watt
(c) Joule
(d) Meter

Joule

11 The unit of work, joule (J) , is equal to:
(a) 1 Newton-meter (1 Nm)
(b) 1 meter per second (1 m/s)
(c) 1 Newton per meter (1 N/m)
(d) 1 kilogram per second (1 kg/s)

1 newton-meter (1 Nm)

12 When is work positive?
(a) When force and motion are in opposite directions
(b) When force and motion are at right angles
(c) When force and motion are in the same direction
(d) When there is no motion despite applied force

When force and motion are in the same direction

13 When is work negative?
(a) When force and motion are in opposite directions
(b) When force and motion are at right angles
(c) When force and motion are in the same direction
(d) When there is no motion despite applied force

When force and motion are in opposite directions

14 What is the SI unit of force?
(a) Kilogram (kg)
(b) Joule (J)
(c) Newton (N)
(d) Meter (m)

Newton (N)

15 Work done will be one ………. if a force of 1 Newton acts on the body and it covers the distance of 1 meter in the direction of force:
(a) Watt
(b) Joule
(c) Newton
(d) Coulomb

Joule

16 One Mega joule is equal to:
(a) 10^3 J
(b) 10^4 J
(c) 10^5 J
(d) 10^6 J

10^6 J

17 Work is a…………..quantity:
(a) Scalar
(b) Vector
(c) Base
(d) All of these

Scalar

18 Work is considered a scalar quantity because:
(a) It involves both magnitude and direction
(b) It only involves magnitude, not direction
(c) It can be negative but not positive
(d) It is measured in kilograms

It only involves magnitude, not direction

19 Work done will be ………. if no force acts on the body:
(a) Maximum
(b) Minimum
(c) Zero
(d) All of these

Zero

20 Work done will be maximum if displacement is ………… to force:
(a) Parallel
(b) Perpendicular
(c) Tangent
(d) All of these

Parallel

21 Work done will be zero if displacement is ………… to Force:
(a) Parallel
(b) Perpendicular
(c) Tangent
(d) Normal

Perpendicular

22 Which situation represents more work being done?
(a) A girl pushing a box across the floor
(b) A boy standing still and holding a box
(c) A person carrying a backpack while walking
(d) A person sleeping on a bed

A girl pushing a box across the floor

23 How work is calculated when a force applied at an angle to the direction of motion?
(a) W = F \times S
(b) W = \frac{F}{S}
(c) W = F \times S × cos(\theta)
(d) W = F \times S × sin(\theta)

W = F \times S × cos(\theta)

### Energy

24 Ability of a body to do work is known as:
(a) Force
(b) Momentum
(c) Power
(d) Energy

Energy

25 Unit of Energy in System International is:
(a) Watt
(b) Joule
(c) Newton
(d) Coulomb

Joule

26 Energy is represented by …………….
(a) W
(b) P
(c) E
(d) L

E

27 Energy is a…………..quantity:
(a) Vector
(b) Scalar
(c) Base
(d) None of these

Scalar

### Kinds of Energy

28 There are ………… basic kinds of energy:
(a) 1
(b) 2
(c) 3
(d) 4

2

29 How are the different forms of energy classified?
(a) As either sun or heat energy
(b) As either potential or kinetic energy
(c) As either heavy or light energy
(d) As either fast or slow energy

As either potential or kinetic energy

#### Kinetic Energy

30 Which of the following scenarios contributes to an object’s kinetic energy?
(a) A stationary car
(b) A stationary ball
(c) A moving cricket ball
(d) A stationary building

A moving cricket ball

31 What determines the ability of a moving object to do work?
(a) Its mass
(b) Its color
(c) Its shape
(d) Its temperature

Its mass

32 How kinetic energy is mathematically calculated?
(a) K.E = mv
(b) K.E = 2mv
(c) K.E = \frac{1}{2} mv^2
(d) K.E = mv^2

K.E = \frac{1}{2} mv^2

33 A bowler during playing cricket throws a ball of mass 2 kg with a velocity of 2 m/s . Its kinetic energy will be:
(a) 4 J
(b) 40 J
(c) 400 J
(d) 4000 J

4 J

34 What will be the kinetic energy of a car of mass 10 kg moving with a velocity of 2 m/s ?
(a) 20000 J
(b) 2000 J
(c) 200 J
(d) 20 J

20 J

35 What will be the kinetic energy of a body if its velocity is doubled?
(a) Doubled
(b) Four times
(c) Eight times
(d) Half

Four times

36 What will be the kinetic energy of a body if its velocity is half?
(a) Doubled
(b) Four times
(c) Eight times
(d) One fourth

One fourth

37 What will be the kinetic energy of a body if its mass is doubled?
(a) Doubled
(b) Four times
(c) Eight times
(d) Half

Doubled

38 What will be the kinetic energy of a body if its mass is half?
(a) Doubled
(b) Four times
(c) Eight times
(d) Half

Half

39 What will be the kinetic energy of a body if it’s both mass and velocity are doubled?
(a) Doubled
(b) Four times
(c) Eight times
(d) One fourth

Eight times

40 When comparing two cricket balls moving towards you, which one can potentially do more work?
(a) The ball with larger mass
(b) The ball with smaller mass
(c) The ball with smaller speed
(d) Both balls have the same kinetic energy

The ball with larger mass

41 Kinetic energy depends on……………. factors.
(a) 1
(b) 2
(c) 3
(d) 4

2

#### Potential Energy

42 Ability of a body to do work due to its position is called:
(a) Kinetic
(b) Potential
(c) Mechanical
(d) All of these

Potential

43 Ability of a body to do work due to its height from the surface of earth is called:
(a) Gravitational Potential
(b) Elastic Potential
(c) Chemical Potential
(d) Attraction

Gravitational Potential

44 When a ball is lifted to a height ‘h’ from the ground, it will possess…………..energy:
(a) Kinetic
(b) Gravitational potential
(c) Mechanical
(d) Elastic potential

Gravitational Potential

45 Which type of potential energy is stored in a book placed on a high shelf?
(a) Gravitational potential energy
(b) Elastic potential energy
(c) Chemical potential energy
(d) All of these

Gravitational potential energy

46 Which form of potential energy is stored in food?
(a) Gravitational potential energy
(b) Elastic potential energy
(c) Chemical potential energy
(d) All of these

Chemical potential energy

47 When an elastic band is stretched, what type of potential energy is stored in it?
(a) Gravitational potential energy
(b) Elastic potential energy
(c) Chemical potential energy
(d) All of these

Elastic potential energy

48 What is the mathematical expression for gravitational potential energy?
(a) P.E = m \times g \times h
(b) P.E = F \times s
(c) P.E = mv^2
(d) P.E = E \times t

P.E = m \times g \times h

49 What is the amount of energy stored when lifting a 0.3 kg brick to a height of 2 m against gravity?
(a) 2.94 J
(b) 5.88 J
(c) 8.82 J
(d) 10.76 J

5.88 J

50 Gravitational potential energy is the product of:
(a) Mass, acceleration, and height
(b) Force, velocity, and time
(c) Distance, time, and velocity
(d) Mass, velocity, and distance

Mass, acceleration, and height

51 Gravitational potential energy is a scalar quantity. What does this mean?
(a) It has both magnitude and direction
(b) It only has magnitude
(c) It only has direction
(d) It has neither magnitude nor direction

It only has magnitude

52 What is the work done against the force of gravity when lifting an object?
(a) W = F \times d
(b) W = m \times g \times h
(c) W = P \times t
(d) W = KE + PE

W = m \times g \times h

53 The work done against gravity to lift an object is stored as:
(a) Gravitational potential energy
(b) Kinetic energy
(c) Elastic potential energy
(d) Mechanical energy

Gravitational potential energy

54 Gravitational potential energy depends on…………….factors.
(a) 1
(b) 2
(c) 3
(d) 4

3

### Forms of Energy

#### Chemical Energy

55 What type of energy is contained within the bonds between atoms?
(a) Gravitational energy
(b) Chemical energy
(c) Kinetic energy

Chemical energy

56 Which form of energy travels as an electromagnetic (light) wave?
(a) Gravitational energy
(b) Chemical energy
(c) Kinetic energy

#### Light Energy

57 What is the source of energy for processes like photosynthesis in plants?
(a) Gravitational energy
(b) Light energy
(c) Kinetic energy
(d) Sound energy

Light energy

#### Electrical Energy

58 What type of energy is associated with charges and involves the movement of electrons?
(a) Chemical energy
(c) Electrical energy
(d) Nuclear energy

Electrical energy

#### Heat Energy

59 Which type of energy transfer occurs when energy travels from a hot body to a cold body?
(a) Electrical energy
(c) Sound energy
(d) Heat energy

Heat energy

60 What type of energy is transferred when a fire burns and warms up a room?
(a) Electrical energy
(c) Sound energy
(d) Heat energy

Heat energy

#### Sound Energy

61 What causes atoms or molecules to vibrate back and forth in a substance, producing sound energy?
(a) Chemical reactions
(c) Electrical current
(d) Sound waves

Sound waves

#### Nuclear Energy

62 What kind of energy is associated with the nucleus of an atom?
(a) Chemical energy
(b) Nuclear energy
(d) Heat energy

Nuclear energy

63 How is nuclear energy utilized in nuclear power stations?
(a) To generate sound energy
(b) To generate electrical energy
(d) To produce chemical reactions

To generate electrical energy

### Law of Conservation of Energy

#### Pole Vault

64 According to the law of conservation of energy, what happens to the total amount of energy in any process?
(a) It can be converted but remains constant
(b) It can be created and destroyed
(c) It can only be created
(d) It can only be destroyed

It can be converted but remains constant

65 How is energy conversion from one form to another described by the law of conservation of energy?
(a) Energy is created in the process
(b) Energy is destroyed in the process
(c) Energy remains constant throughout the process
(d) Energy is randomly transformed

Energy remains constant throughout the process

66 In the case of a diver on a springboard, which type of energy is stored in the body of the diver?
(a) Gravitational potential energy
(b) Kinetic energy
(c) Elastic potential energy
(d) Chemical energy

Chemical energy

67 What form of energy is stored in a bent diving board after the diver bends it?
(a) Gravitational potential energy
(b) Kinetic energy
(c) Elastic potential energy
(d) Chemical energy

Elastic potential energy

68 How is the potential energy of water stored at a height converted into electricity?
(a) Through nuclear reactions
(b) Through chemical reactions
(c) By making it fall on a turbine
(d) By heating the water

By making it fall on a turbine

69 What energy conversion takes place when a pole vaulter runs and plants the pole to vault over a bar?
(a) Kinetic energy to potential energy
(b) Potential energy to kinetic energy
(c) Elastic potential energy to gravitational potential energy
(d) Gravitational potential energy to kinetic energy

Kinetic energy to potential energy

70 When a weightlifter lifts a barbell over her head, what type of energy is primarily used?
(a) Kinetic energy
(b) Gravitational potential energy
(c) Elastic potential energy
(d) Chemical energy

Chemical energy

71 For maintaining the body temperature, what type of energy is used?
(a) Heat
(b) Electrical
(c) Chemical
(d) Mechanical

Heat

72 What type of energy is stored in the water stored in a dam?
(a) Elastic potential energy
(b) Gravitational potential energy
(c) Kinetic energy
(d) Mechanical energy

Gravitational potential energy

73 Increase in K.E is equal to:
(a) Increase in P.E
(b) Decrease in P.E
(c) Both A & B
(d) None of these

Decrease in P.E

74 Increase in P.E is equal to:
(a) Increase in K.E
(b) Decrease in K.E
(c) Both A & B
(d) None of these

Decrease in K.E

75 Decrease in K.E is equal to:
(a) Increase in P.E
(b) Decrease in P.E
(c) Both A & B
(d) None of these

Increase in P.E

76 Decrease in P.E is equal to:
(a) Increase in K.E
(b) Decrease in K.E
(c) Both A & B
(d) None of these

Increase in K.E

### Einstein’s Energy Mass Equation

77 What is Einstein's \ mass-energy equation?
(a) E = mc
(b) E = mc^2
(c) E = mc^3
(d) E = mc^4

E = mc^2

78 In Einstein’s equation E = mc^2 , what does "E" represent?
(a) Energy
(b) Mass
(c) Speed of light
(d) Momentum

Energy

79 What is the unit of energy in Einstein’s equation E = mc^2 ?
(a) Joules (J)
(b) Kilograms (kg)
(c) Meters per second (m/s)
(d) Watts (W)

Joules (J)

80 What does "m" represent in Einstein’s equation E = mc^2 ?
(a) Energy
(b) Mass
(c) Speed of light
(d) Momentum

Mass

81 What is the constant value of the speed of light in meters per second (m/s) ?
(a) 1 \times 10^6 m/s
(b) 3 \times 10^8 m/s
(c) 5 \times 10^{10} m/s
(d) 9 \times 10^{12} m/s

3 \times 10^8 m/s

82 How is the speed of light represented in Einstein’s equation E = mc^2?
(a) s
(b) v
(c) c
(d) a

c

83 According to Einstein’s mass-energy equivalence, what physical entities are the same and can be changed into each other?
(a) Mass and energy
(b) Mass and momentum
(c) Mass and speed
(d) Mass and force

Mass and energy

84 In Einstein’s equation, what is the relationship between energy and mass?
(a) Energy is inversely proportional to mass
(b) Energy is equal to mass
(c) Energy is proportional to mass
(d) Energy is the square root of mass

Energy is proportional to mass

85 What are the units of the speed of light (c) in Einstein’s equation?
(a) m/s
(b) m/s^2
(c) m^2/s^2
(d) m^3/s^3

m/s

### Major Sources of Energy

#### Hydroelectric Generation

86 What is the term for the transformation of energy from one source into a useful form?
(a) Energy exchange
(b) Energy utilization
(c) Energy transformation
(d) Energy conversion

Energy transformation

87 Which of the following is NOT a major source of energy?
(a) Geothermal energy
(b) Solar energy
(c) Wind energy
(d) Food energy

Food energy

88 Which of the following is a fossil fuel?
(a) Biomass
(b) Geothermal energy
(c) Natural gas
(d) Nuclear energy

Natural gas

89 Which energy source is associated with the remains of ancient plant and animal life?
(a) Geothermal energy
(b) Fossil fuel
(c) Wind energy
(d) Nuclear energy

Fossil fuel

90 Fossil fuels are consumed in more than ………. of the world demand for energy.
(a) 80%
(b) 90%
(c) 50%
(d) 10%

80%

91 What is the most abundant fossil fuel in the world?
(a) Oil
(b) Natural gas
(c) Coal
(d) Petroleum

Coal

92 What process is used to convert crude oil into products like gasoline and heating oil?
(a) Fission
(b) Photosynthesis
(c) Refinement
(d) Combustion

Refinement

93 What is the primary advantage of natural gas as an energy source?
(a) It produces no waste gases
(b) It is abundant in supply
(c) It is easy to transport
(d) It is a renewable resource

It is easy to transport

94 Which type of energy resource is produced when solar energy is converted into plant matter?
(a) Fossil fuels
(b) Nuclear energy
(c) Geothermal energy
(d) Biomass

Biomass

95 Which of the following is an example of biomass?
(a) Crude oil
(b) Natural gas
(c) Plant matter
(d) Coal

Plant matter

96 What type of energy is harnessed from Earth’s core in geothermal energy?
(a) Solar energy
(b) Gravitational potential energy
(c) Nuclear energy
(d) Thermal energy

Thermal energy

97 How is the kinetic energy of the wind used to generate electricity?
(a) With solar cells
(b) By large turbines
(c) Through nuclear fission
(d) By photosynthesis

By large turbines

98 What energy resource is derived from the energy trapped during Earth’s formation?
(a) Solar energy
(b) Geothermal energy
(c) Wind energy
(d) Nuclear energy

Geothermal energy

99 How is solar energy harnessed to produce electricity?
(a) Using solar cells
(b) Through nuclear fission
(c) By combustion of fossil fuels
(d) By converting thermal energy

Using solar cells

100 What type of energy is generated when the kinetic energy of flowing water is converted into electric energy?
(a) Thermal energy
(b) Gravitational potential energy
(c) Hydroelectric energy
(d) Wind energy

Hydroelectric energy

101 What is the process of splitting large atoms into smaller pieces to release energy?
(a) Combustion
(b) Fission
(c) Photosynthesis
(d) Fusion

Fission

102 What is the primary advantage of using solar energy?
(a) It is completely pollution-free
(b) It requires minimal land area
(c) It doesn’t require any technology
(d) It is a non-renewable resource

It is completely pollution-free

103 What process converts the heat produced by nuclear fission into electricity?
(a) Combustion
(b) Photosynthesis
(c) Steam turbine
(d) Solar cells

Steam turbine

### Efficiency

104 Efficiency is defined as the ratio of:
(a) Total energy input to total energy output
(b) Useful energy output to total energy input
(c) Total energy input to useful energy output
(d) None of these

Useful energy output to total energy input

105 What is the efficiency formula in terms of energy?

(a) Efficiency = \frac{Useful \ energy \ output} {Energy \ input}

(b) Efficiency = \frac{Energy \ input}{Useful \ energy \ output}

(c) Efficiency = \frac{(Useful \ energy \ output - Energy \ input)}{Energy \ input}
(d) All \ of \ these

Efficiency = \frac{Useful \ energy \ output} {Energy \ input}

106 What is the efficiency formula in terms of work?

(a) Efficiency = \frac{(Useful \ work \ output - Work \ input)}{Work \ input}

(b) Efficiency = \frac{Work \ input}{Useful \ work \ output}

(c) Efficiency = \frac{Useful \ work \ output}{Work \ input}
(d) All of these

Efficiency = \frac{Useful \ work \ output}{Work \ input}

107 Why is it not possible to have a machine with 100% efficiency?
(a) Because machines always have friction
(b) Because machines require energy input
(c) Because machines waste energy as heat
(d) Because machines are not designed for efficiency

Because machines waste energy as heat

108 What is the primary reason why incandescent light bulbs are not very efficient?
(a) They produce too much light energy
(b) They produce a lot of waste thermal energy
(c) They convert energy into chemical potential energy
(d) They have a low input energy

They produce a lot of waste thermal energy

109 How is efficiency expressed as a percentage?

(a) Efficiency = \frac{Useful \ energy \ output}{Energy \ input}

(b) Efficiency = \frac{Energy \ input}{Useful \ energy \ output}

(c) Efficiency = \frac{Useful \ energy \ output}{Energy \ input} \times 100 %

(d) Efficiency = \frac{Energy \ input}{Useful \ energy \ output} \times 100 %

Efficiency = \frac{Useful \ energy \ output}{Energy \ input} \times 100 %

110 What type of energy is typically produced as waste when efficiency is not high?
(a) Light energy
(b) Thermal energy
(c) Kinetic energy
(d) Potential energy

Thermal energy

111 Which of the following is an example of a machine that converts chemical potential energy into kinetic energy?
(a) Automobile engine
(b) Electric generator
(c) Wind generator
(d) Home gas furnace

Automobile engine

112 What is the efficiency of an incandescent light bulb?
(a) 5%
(b) 20%
(c) 50%
(d) 95%

5%

113 What is the efficiency of a fluorescent lamp?
(a) 5%
(b) 20%
(c) 50%
(d) 95%

20%

114 Which device has high efficiency?
(a) Electric generator
(b) Electric motor
(c) Wind generator
(d) Automobile engine

Electric generator

### Power

115 The rate at which work is done is known as:
(a) Energy
(b) Power
(c) Momentum
(d) Work

Power

116 The SI unit of power is:
(a) Watt
(b) Joule
(c) Newton
(d) Coulomb

Watt

117 1 \ watt is equal to………………..
(a) 1 J/s
(b) 1 J.s
(c) 1 m/s
(d) All \ of \ these

1 J/s

118 Power is represented by………
(a) E
(b) P
(c) W
(d) L

P

119 Power is a………….quantity.
(a) Scalar
(b) Vector
(c) Time independent
(d) None of these

Scalar

120 The mathematical expression for power is…………..
(a) W = F.s
(b) V = \frac{s}{t}

(c) P = \frac{W}{t}
(d) None \ of \ these

P = W/t

121 How many watts are equal to one horsepower (1 hp) ?
(a) 550 W
(b) 746 W
(c) 1000 W
(d) 3600 W

746 W

122 Which unit of power is often used to measure the power of engines and motors?
(a) Kilowatt hour (kWh)
(b) Joule per second (J/s)
(c) Horsepower (hp)
(d) Foot-pound per second (ft.lb/s)

Horsepower (hp)

123 One horsepower (1 hp) is equal to…………..
(a) 550 ft.lb/s
(b) 1000 J/s
(c) 700 W
(d) 3600 s

550 ft.lb/s

124 In British system, the unit of power is……………..
(a) J/s
(b) Watt
(c) ft.lb/s
(d) Second

ft.lb/s

125 Light bulbs are often rated in terms of their…………….
(a) Energy
(b) Voltage
(c) Resistance
(d) Power

Power

126 “kWh” is the unit of………
(a) Power
(b) Energy
(c) Time
(d) Velocity

Energy

127 1 \ kWh is equal to……………
(a) 5 \times 105 \ J
(b) 3.6 \times 106 \ J
(c) 2 \ J
(d) 1000 \ J

3.6 \times 106 \ J

128 What will be the power of a machine doing 10 \ J work in 5 \ seconds?
(a) 2 W
(b) 10 W
(c) 25 W
(d) 50 W

2 W

129 How much work a 5 \ watt motor do in 5 \ seconds .
(a) 25 J
(b) 30 J
(c) 50 J
(d) 100 J

25 J

130 A motor exerts a force of 100 \ N to move an object a distance of 5 \ meters \ in \ 10 \ seconds . What is the power exerted by the motor?
(a) 1000 W
(b) 500 W
(c) 50 W
(d) 25 W 