Conservation Of Energy Part 2

CONVERSION OF ENERGY FROM ONE FORM TO ANOTHER

Toasting Bread:

*  Electricity → heat energy

Charging a Cell Phone Battery:

*  Electricity→ chemical energy + heat energy

Solar Cells:

*  Light energy (Sunlight) → electricity + heat energy

Burning:

*  Chemical energy → heat energy  + light energy

Photosynthesis:

*  Light energy (Sunlight) → chemical energy

Internal Combustion Engine:

*  Chemical energy → kinetic energy + heat energy + light energy + sound energy

ENERGY TRANSDUCERS

These are machines that change energy from one form to another. They are also called energy converters. Examples include toasters, light bulbs, and televisions.

SOURCES OF ENERGY

The main sources of energy are:

*  Sun

*  Fossil Fuels

*  Water

*  Wind

*  Atoms – Nuclear

*  Underground heat – Geothermal

1) THE SUN

Solar energy is energy from the Sun. It is our main source of energy. It releases light and heat energy. Light energy can be changed into other forms of energy using:

• Solar cells
• Solar panels
• Solar furnace

SOLAR CELLS

Solar cells trap sunlight and change it into electricity. This is called Photovoltaics. It is used in watches, calculators, and traffic lights.

SOLAR PANELS

Solar panels ate black and are placed on roof tops. They trap heat used to heat water.

SOLAR FURNACE

In a solar furnace, many mirrors direct energy onto one small spot. This spot gets very hot – thousands of degrees in temperature. In a solar furnace, metals are melted and electricity is produced.

2) FOSSIL FUELS

Fossil fuels are formed from the remains of dead plants and animals buried for millions of years. They are non-renewable. There are three (3) main types of fossil fuels: coal, crude oil, and natural gas. Fossil fuels is the source of energy we use most on Earth.

3) WATER

Rain has gravitational potential energy. In hydroelectric power stations falling water turns turbines which produce electricity.

4) WIND

Wind is moving air. It turns turbines to produce electricity.

5) NUCLEAR ENERGY

In nuclear fission heavy elements are broken down and energy is released in the form of heat. This heat is used to boil water. Steam is produced. This steam turns turbines which produce electricity. Nuclear fission is dangerous. It releases radiation which causes cancer and destroys plants and animals.

6) GEOTHERMAL ENERGY

This is heat energy from the Earth’s crust. It can be found in volcanoes, geysers, and hot springs. Steam from the Earth is used to turn turbines to produce electricity.

HOW ELECTRICITY IS PRODUCED

Water is boiled. The water turns to steam. The steam turns turbines. The turbines are attached to a generator. The generator produces electricity.

ENERGY USAGE

HOME:

*  Past – candle, oil lamp

*  Present – computer, television, cell phone, radio, microwave, washing machine, toaster

WORK – FARM:

*  Past –  animals used in the field

*  Present – tractor, fertilizer spreader, milking machine

WORK – OFFICE:

*  Present – fax machine, printer, computer, microwave, refrigerator, photocopier

INDUSTRY

*  Past – smoke signals

*  Present – electronic equipment and satellites

TRANSPORT

*  Past – horse and cart

*  Present – cars, trucks, planes, trains, ships

LEISURE

*  Past – a board game, outside games such as cricket, football

*  Present – computer game, cell phone activities, internet browsing

ENERGY CONSERVATION

*  Turn off lights and appliances when not in use

*  Reduce, reuse, recycle

*  Use catalytic converters to change harmful vehicle exhaust into harmless substances

*  Use renewable forms of energy such as solar, wind, and water

VELOCITY

Velocity is the speed and direction of a moving object.

MOMENTUM

Momentum is an object’s mass × its velocity.

COLLISIONS

The result of a collision is based on each object’s momentum.

REFLECTION OF LIGHT

Light can be reflected at:

• Plane/ Flat surfaces – rays of light stay parallel
• Convex curved surfaces – rays of light spread apart
• Concave curved surfaces – rays of light come together

FOCUS/ FOCAL POINT OF A MIRROR

This is the point where light rays meet. It is used in driving mirrors and headlamps.

NEWTON’S CRADLE AND THE CONSERVATION OF MOMENTUM

This is an object that shows how energy and momentum are conserved.