Energy exists in many forms and can be transferred or converted from one form to another. However, the total amount of energy remains constant. Examples of energy conversions include chemical energy being converted to heat energy during combustion, and kinetic energy being converted to gravitational potential energy when a pendulum swings. As the world's energy consumption increases, there is a need to develop sustainable energy sources and conserve existing resources.

3. 16.1 What is Energy?
Energy is the ability to do work .
We use energy to live and function .
Without energy, living systems will die
and non-living systems will not function .
The SI unit for energy is Joules ( J ).

4. 16.2 Forms of Energy
Energy exists in many forms.
Energy in Action Stored Energy
Kinetic Energy Potential Energy
Heat Energy Gravitational Potential
Energy
Light Energy Elastic Potential Energy
Sound Energy Chemical Energy
Electrical Energy Nuclear Energy

5. Kinetic Energy
Kinetic energy is the energy that a
body has due to its motion.
Any object that moves has kinetic
energy.
Eg. A moving car has kinetic energy

6. Heat Energy
Heat energy is the energy that flows
from a region of higher temperature
to a region of lower temperature.
Eg. A hot cup of tea contains heat
energy.

7. Light Energy
Light is the energy that enables us
to SEE.
Eg. Light energy is given out by a
fire.

8. Electrical Energy
Electrical energy is a form of energy
that involves the flow of electric
charges.

9. Gravitational Potential
Energy
Gravitational Potential Energy is the
energy an object has because of its
position or location.
Any object that is raised from a
lower position to higher position
gains gravitational potential energy.

10. Elastic Potential Energy
Elastic Potential Energy is the
energy an object has when it is
stretched or compressed.
Eg. A stretched rubber band or a
compressed spring has elastic
potential energy.

11. Chemical Energy
Chemical energy is the energy
stored in fuel (eg. Petrol, Batteries,
Food) that can be released through
chemical reaction.

12. Nuclear Energy
Nuclear energy is a form of energy
stored in the nuclei of atoms.
Eg. Atomic bombs, nuclear reactor
in a nuclear power plant

13. 16.3 Conversion of Energy
Energy can be converted from
one form to another.

14. Examples of Conversion
of Energy
Oven Toaster
Electrical Energy  Heat Energy

15. Examples of Conversion
of Energy
Television
Electrical Energy  Light Energy
and Sound
Energy

16. Examples of Conversion
of Energy
Burning Matchstick
Chemical Energy  Heat Energy
and Light
Energy

17. Examples of Conversion
of Energy
Falling Apple
Gravitational  Kinetic
Potential Energy Energy

18. Examples of Conversion
of Energy
Atomic Bomb
Nuclear Energy  Heat Energy,
Light Energy
and Sound
Energy

19. Examples of Conversion
of Energy
A person shooting a rubber band
Elastic Potential  Kinetic
Energy Energy

20. 16.4 Principle of
Conservation of Energy
Principle of Conservation of energy
states that:
Energy cannot be created or destroyed.
It is transferred from one body to another
or transformed from one form to another.
Total energy remains constant.

21. Example: Piling
1. The pile hammer is raised to a
height. It gains gravitational
potential energy.
2. During the fall, the gravitational
potential energy energy is
changed to kinetic energy.
3. As the hammer hits the pile,
majority of the kinetic energy is
transferred to the pile driving
the pile into the ground. While
some is converted to sound &
heat energy.

22. Example: Swinging of Pendulum
Pendulum bob loses
all its kinetic energy
Pendulum bob has its
and gain maximum
maximum gravitational
gravitational potential
potential energy and
energy as it comes to
zero kinetic energy at
rest at its maximum
Pendulum bob loses
the starting position
height.
gravitational potential Pendulum bob starts to
energy and bob loses all its
Pendulum gains lose its kinetic energy
kinetic energypotential energy
gravitational as it and gain gravitational
swings down maximum
and gain its potential energy as it
kinetic energy at the lowest position swings up

23. Power Station
A power station uses fossil fuels
such as coal, natural gas and oil.
When these fossil fuels are
burnt, the chemical energy
stored in these fuels is released
to boil water to form steam.
The moving steam turns the
generator.
When the generator turns,
electrical energy is produced.

24. Power Station
A power station uses fossil fuels
such as coal, natural gas and oil.
When these fossil fuels are
burnt, the chemical energy
stored in these fuels is released Energy Conversion
to boil water to form steam. in Power plant
The moving steam turns the Chemical Energy
generator.
Heat Energy
When the generator turns,
electrical energy is produced.
Kinetic Energy
Eletrical Energy

25. Different types of Power Station
A geothermal power plant
uses heat from the earth.
A hydroelectric power station
uses energy from falling water.
A wind turbine uses energy
from wind to turn the
turbines.

26. Conserving Energy
With rapid growth in populations,
urbanisation, industrialisation and
globalisation, the world is
consuming more energy.
There is a need to conserve energy
and use it wisely.

27. Free but expensive
sources of energy
Energy from the Sun, wind, rain, tides, nuclear
fuels and heat from inside the Earth can be
harnessed to do work and improve our quality
of life.
These alternative sources of energy are clean
and do not run out.
However, they are expensive or unsuitable to
harness in some places.

28. Plants and waste from
animals
Fuels such as biogas and alcohol are
derived from biomass (plant materials
or wastes from living things)

29. Risky Sources
The production of electrical energy
using nuclear fuels is cleaner than
that using coal or oil.
However, there is a fear of exposure
to harmful radiation should an
accident happen in a nuclear power
plant.

30. In Singapore….
Singapore is a small country without
natural resources.
Although it is one of the major oil refinery
centres of the world, it has to import oil and
gas from other countries for production of
electrical energy.
There is a need to conserve energy,
especially for Singapore.

31. Caring for Mother Nature
Humans’ need for more and more energy
has sparked the global concern that non-
renewable energy sources such as fossil
fuels will run out one day.
The use of such fuels has heightened
environmental concerns regarding air and
water pollution as well as global warming.