Chapter 16:

Energy Forms and Conversions

Before we move on,

We have…

Representing the video clip available

                                                                               

state what is meant by energy

describe different forms of energy and how energy changes from one form to another

infer that energy is conserved and can be transformed from one form to another

appreciate the need for Singapore – which has no natural resources of her own – to conserve energy

Lesson Outline

                                      

Energy types

electrical

light

heat

kineticpotentialnuclear

sound

There are different forms of energy:

16.1 Energy and Its Various Forms

Energy is the ability to do work.

You make use of different types of energy to help you do work in your daily life.

chemical

                                      

Potential energy is a form of stored energy.

Potential energy

1 Gravitational potential energy

2 Chemical potential energy

3 Elastic potential energy

(a) Potential Energy

Elastic potential energy

Gravitationalpotential energy

Chemical potential energy

(1) Gravitational potential energy•The airplane's stored energy is due to its elevated position in a region where there is gravity. This type of potential energy is called gravitational potential energy.

(2) Elastic potential energy•This is found in stretched or compressed elastic objects (e.g., compressed spring)

(3) Chemical potential energy•The stored energy in the food is called chemical potential energy.

•It is found in fuels, food, batteries and in living things. It is only released when a chemical reaction takes place.

Kinetic Energy is the energy of a body due to its motion.

(b) Kinetic energy

•The amount of the energy is directly proportional to the mass of an object.

Cars and bullets can cause damage at high speeds due to high kinetic energy.

(c) Light energy

•Light is a form of energy that allows us to see things and for plants to make food.

•Optical fibres also make use of light to transmit huge amounts of information over long distances at high speeds.

An optical fibre is a glass or plastic fibre designed to guide light along its length.

Did You Know??

(d) Sound energy•It is produced by vibrating objects. It can travel through solids, liquids and gases but not vacuum.

•Loud sounds and noise cause sound pollution.

•Sounds produced by musical instruments are pleasant to our ears.

(e) Electrical energy•It involves the flow of an electric current.

•It is widely used as it can be easily generated and transmitted over long distances and be converted into other forms of energy to do work.

(f) Heat energy

• It is a form of energy comes from the internal motion of the particles in a body; it flows from a region of higher temperature to a region of lower temperature.

• It can travel through solids, liquids, gases and vacuum.

(g) Nuclear energy• It is a form of energy that comes from a nuclear reaction.

Two types of nuclear reaction:

- Nuclear fission: Large amount of energy is released when nuclei of small atoms combine to form heavier ones.

(e.g., energy of the Sun)

- Nuclear fusion: Energy is produced when the nucleus of a heavy atom is split into smaller ones. (e.g., nuclear power stations)

• It can be disastrous if it is abused.

(e.g., nuclear bombs used in World War II)

                                                                               

• The energy is converted from one form to another when work is done. For e.g.,

Solar panels capture light energy from the Sun, and convert it to electricity.

Green plants undergo photosynthesis to convert light energy into chemical energy in the form of food.

16.2 Conversion of Energy

• In fact, energy is never lost; it is only converted from one form to another. This is stated in the Law of Conservation of Energy: Energy can not be created nor destroyed.

• Very often, it takes a whole series of energy conversions to do a certain job.

• For example, just to get the energy to make a piece of toast, there are several energy conversions involved.

Did You Know ??

                                                                               

Energy cannot be created nor destroyed. It can be converted from one form into another, and each time, work is always done.

• In any closed system, the total amount of energy remains constant before and after work is done, regardless of any process taking place.

• When more work is done, more energy is converted.

Laws of Conservation of Energy

Go to Video 16.1