ENERGYForms and Changes

What is Energy?

“Energy is the ability to do work.”

We use energy to do work and make all movements. When we eat, our bodies transform the food into energy to do work. When we run or walk or do some work, we ‘burn’ energy in our bodies. Cars,

planes, trolleys, boats, and machinery also transform energy into work. Work means moving or lifting something, warming or lighting something. There are many sources of energy that help to run the various machines invented by man.

TYPES OF ENERGY

Potential Energy “Energy at rest.”• An object can store energy

as the result of its position.• The higher an object is,the

more potential energy it has.

Kinetic Energy“Energy of motion.”• If something is moving it

has kinetic energy.• The faster an object is

moving,the more kinetic energy it has.

TYPES OF ENERGY

Potential EnergyAs this roller coaster car moves to

the top of the hill,it gains potential energy.As it falls,its kinetic energy increases and its potential energy decreases.

Kinetic Energy

An airplane flying through the air has more kinetic energy than a person riding a bicycle.

What are some Forms of Energy?

o Mechanicalo Solar/Radianto Lighto Heato Electricalo Soundo Chemicalo Nuclear

MECHANICAL ENERGY

• Mechanical Energy is the combination of all the potential and kinetic energy that something has.

• The energy we use everyday to physically move things.

• When a person bikes through a mountain/hill, it possesses a mechanical energy.When going up and down to the top of a mountain/hill,it is kinetic.When on the top,it is potential energy.

SOLAR/RADIANT ENERGY• Solar Energy comes from the sun.The word solar

means “comes from the sun”.People use solar cells that change light energy from the sun into electricity.o Solar calculators o Solar panels to heat swimming poolso Solar panels that provide light and power appliances in

homes or other buildingsWithout solar energy,Earth would be just a ball of frozen rock with no

life.The sun is the source of almost all energy on Earth.Light from the sun helps plants make food and oxygen.Its energy is stored in fossil fuels that come from long-dead plants and animals.The sun’s energy is also the source of weather.

LIGHT ENERGY• Light energy is the energy that is inherent from light.

It can also be viewed as a means by which electromagnetic radiation is perceived from the natural light sources e.g. the sun to living things.

This energy is carried in discrete packets called photons i.e. In living plants for example, the lightenergy is what splits organic molecules to make chemical energy in a process called photosynthesis.

HEAT ENERGY• A form of energy that is transferred by a difference in

temperature.Heat energy is the energy stored within atoms, that can be produced when the organism vibrates and causes friction.

A hot object is one whose atoms and molecules are excited and show rapid movement. A cooler object's molecules and atoms will be less excited and show less movement.

ELECTRICAL ENERGY• Electrical energy is the energy carried by moving

electrons in an electric conductor. It cannot be seen, but it is one of our most useful forms of energy because it is relatively easy to transmit and use.

SOUND ENERGY

• Sound is energy in the form of vibrations that travel through matter.When a vibration reaches a particle of matter,that particle starts to vibrate,too.In this way,sound vibrations can spread out,not just in a straight line,but in all directions.

CHEMICAL ENERGY

• “Energy stored fuel.”• It can be release by a chemical reaction,such as

burning or digestion.It is needed to change its potential into kinetic energy.

Our muscles get energy from the food we eat.The

potential energy stored in food is chemical energy.When it’s released,it gives us kinetic energy to move.

NUCLEAR ENERGY• Nuclear energy originates from the splitting of

uranium atoms in a process called fission. At the power plant, the fission process is used to generate heat for producing steam, which is used by a turbine to generate electricity.

ENERGY TRANSFORMATION

• A change from one form of energy to another is called energy transformation.• Law of Conservation of Energy states that energy can

change form, but it cannot be created or destroyed. Therefore, the total amount of energy stays the same.

• In energy transformations, some energy is always lost to the environment as thermal energy.

Examples of Energy Transformation:A television changes electrical energy into sound and light energy.

A toaster changes electrical energy into thermal energy and light.

A car changes chemical energy from fuel into thermal energy and mechanical energy.

A flashlight changes chemical energy from batteries into light energy.

When you speak into your telephone, sound energy from your voice is changed into electrical energy. The electrical energy is then converted back into sound energy on another phone, allowing someone to hear you.

Light energy is converted into electrical energy using solar panels.

Campfires convert chemical energy stored in wood into thermal energy, which is useful for cooking food and staying warm.

Nuclear energy generates a tremendous amount of thermal energy, which can be converted into electrical energy in a nuclear power plant.

Thermal Energy Transformation• CONDUCTION- is the heating of an object from direct

contact between a heat source and the object. EXAMPLE: A pan getting hot from the stove.

• CONVECTION- is heating of an object through the movement of a fluid (a gas or liquid).EXAMPLE: The thermal currents in the ocean or in the atmosphere.

• Radiation-is the heating of an object by radiant energy traveling through space by electromagnetic waves. EXAMPLE:The thermal energy coming to the Earth from the Sun through infrared waves.

Some applications of thermal energy transfer include: heat engines (cars, lawn

mowers), thermostats, refrigerators, and heat pumps.

SCIENCE WORDSEnergy Chemical energyKinetic energy Nuclear energyPotential energy Energy transformationMechanical energy Law of conservation ofSolar/Radiant energy energy Light energy ConductionHeat energy ConvectionElectrical energy RadiationSound energy