Different forms of energy and the energy conservationCopy

Learning Objectives

Identify changes in kinetic, gravitational potential, chemical, elastic (strain), nuclear and internal energy that have occurred as a result of an event or process
Recall and use the expressions kinetic energy = ½mv^2 and change in gravitational potential energy = mgΔh
Recognise that energy is transferred during events and processes, including examples of transfer by forces (mechanical working), by electrical currents (electrical working), by heating and by waves
Apply the principle of conservation of energy to simple examples
Apply the principle of conservation of energy to examples involving multiple stages
Explain that in any event or process the energy tends to become more spread out among the objects and surroundings (dissipated)

Contents to learn

Energy
It is the ability of a system to do work.

Energy exists in different forms.

It can not be created or destroyed. It always remains conserve.

It can be converted from one form to another form.

All the energies are measured in Joules (J) in S.I.

Remember, WattsSecond or KiloWattsHours are also units of energy.

Different types of energy

Strain energy:
The word strain means stretched. Strain energy can be stored in stretched springs and rubbers etc.

Chemical energy:
In any object the atoms are held together by forces, that are called bonds.

In some materials such as fuels and explosives these bond are found to be shorter or longer.

This store energy can be released by breaking up these bonds.

Nuclear energy:
The energy in a nucleus of an atom is stored in strong bond between the particles of nucleus.

This energy can be released by splitting the nucleus into two small nuclei. This is done in nuclear power stations.

Internal energy:
This is continued within an object and makes the difference between the object being hot or cold. Hot object has more internal energy.

Electrical energy:
Electrical currents carry electrical energy from one place to another.

It can be turned into kinetic internal energy in heaters / resistors etc.

Light energy:
Light carries energy as it travels.

This will be turned into internal energy if it strikes most objects.

It can also be used to generate electrical energy.

Sound waves:
These carry a very small amount of energy from the source of noise.

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

Kinetic energy can be calculated by using the following formula

Kinetic Energy = (1/2) m v2

Kinetic enery is also measured in Joules.

Potential energy
Different types of fuels store energy for doing work. This stored or hidden energy is called potential energy(P.E.)

If a spring or rubber is stretched the spring will have potential energy. This is called elastic potential energy(or strain energy).
If a load is raised above the ground, it will have gravitational P.E .

Gravitational potential energy can be calculated using the formula

Gravitational P.E= mass X gravitational field streght X height

P.E = m X g X h

Gravitational potential energy is energy an object possesses because of its position in a gravitational field.

Law of conservation of energy
This law states that “energy can not be created or destroyed”.

It can be changed from one form to another form, but total energy is always canserved.

The total energy at the start and at the end of any system must have the same value.

For example, the train takes electrical energy and converts it mainly into K.E, but also into sound and internal energy.

We can also use this principal to observe what happens when K.E and P.E are converted from either one to the other.

Curriculum

Cambridge IGCSE Physics

Different forms of energy and the energy conservationCopy

Different types of energy

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