Energy Chapter 38

What is Energy? Energy is the ability to do work. The unit of energy is the Joule(J).

Different forms of Energy  Potential Energy-stored energy in a body.eg coiled spring  Kinetic Energy- energy that moving objects have.  Heat Energy-Hot air rises.  Light Energy-Crooks radiometer or solar powered calculator.  Sound Energy-  Electrical Energy-may be converted to Light, heat sound.  Chemical Energy-energy stored in food, oil etc.  Nuclear Energy-Energy released from the nuclei of atoms.

Law of Conservation of Energy Energy cannot be created or destroyed, but can only change from one form to another

Energy can be changed from one form to another. For example: Chemical energy in food is converted to thermal energy and kinetic energy by our bodies. Energy transfer What other energy transfers can you think of? Gravitational energy in a ball is converted to kinetic energy when it falls to the ground.

burning match portable torch microphone radio television catapult mobile phone car chemical → heat and light sound → electrical electrical → sound and heat electrical → sound and light and heat elastic → kinetic and heat chemical → sound and microwaves (EM radiation) and heat chemical → kinetic and sound and heat In all these transfers the energy is not lost, it is conserved. Energy cannot be destroyed or created. What energy transfer takes place in each device? What is the energy transfer?

Name the Energy Conversions ?

Energy needs and Heat Loss Heat loss in a House where no precautions have been taken to save Heat.

Glass Fibre on the attic floor

Lagging on hot water tank and pipes

Air cavity wall insulation

Draught excluders on doors and Windows

Double Glazing on windows

Sources of Energy The Energy sources used to produce the worlds electricity

Non renewable sources of energy Non renewable sources of energy are fossil fuels (coal, oil, natural gas). Once used they cannot be replaced. How we have used fossil fuels over the centuries.

This is how long coal, gas and oil will last if we continue to use them at the present rate. Fossil fuel reserves

Renewable sources of energy Renewable sources of energy are those that will never be used up. Examples: Solar energy Hydro-electric energy Wind energy Wave energy Biomass energy-trees and plants Tidal energy Geothermal Energy-heat from ground Hydro-electric power

What is Biomass?Biomass? Biomass energy comes from trees and plants. In this diagram plants are being broken down by bacteria to produce methane(natural gas)

What is Geothermal energy?Geothermal energy Geothermal energy is energy that is got from the ground. The hot water or steam that is got from the ground is sent to turbines to produce electricity. Iceland uses a lot of geothermal energy.

Schematic representation of an ideal geothermal system.

The Sun The Sun is the primary source of Energy. Energy radiated to the earth in the form of light and Heat provides us with all of the energy we use.

Energy from the sun

Nuclear Energy Nuclear energy is the energy released from the nuclei of atoms. Nuclear fission is used in electric power stations. This involves the splitting of large atoms like Uranium, and the enormous energy released is converted to electrical energy.

Nuclear fusion Nuclear fusion occurs in the sun. Here nuclei of light atoms combine to produce enormous amounts of energy.

How a nuclear reactor works

Advantages and dis-advantages of nuclear energy Advantages –Medicine-kill cancer cells. –Radiation sterilises food. –Production of Electricity –Will not run out like fossil fuels Disadvantages –Difficult to get rid of waste –Radiation can kill –Accidents like Chernoble