ENERGY Grade 8 Integrated Science

Give examples of the various kinds of energy Objectives Define energy and fuel Give examples of the various kinds of energy Show how energy is converted Distinguish between renewable and non-renewable energy Discuss uses of the sun’s energy Draw the electromagnetic spectrum Discuss the harmful effects of the sun’s energy Describe how crude oil is formed State the uses of crude oil and other fuels Discuss the importance of energy conservation List ways of conserving energy Calculate Energy efficiency

WHAT IS ENERGY? Energy is the ability to do work Energy can also be considered as the ability to bring about a change

TYPES OF ENERGY? Kinetic/movement energy (KE) Potential/stored energy (PE) Electrical energy Chemical energy (CE) Solar energy Nuclear energy Light energy Heat energy Sound energy

THE LAW OF ENERGY CONSERVATION ENERGY CONVERSION THE LAW OF ENERGY CONSERVATION Energy can neither be created nor destroyed, but can be changed or converted from one form to another.

A BLENDER CHANGES ELECTRICAL ENERGY INTO MOVEMENT ENRGY SOUND AND HEAT ENERGY CONVERSION A BLENDER CHANGES ELECTRICAL ENERGY INTO MOVEMENT ENRGY SOUND AND HEAT Sound energy Electrical Energy Heat energy Movement energy BLENDER

ENERGY FROM THE SUN The sun is a huge ball of ‘burning gas’ It has a very high temperature of approximately 150 million degrees Celsius at its centre.

USES OF THE SUN’S ENERGY Vitamin D Provides light Provides heat which sustains life To grow food To dry clothes To produce electricity

ELECTROMAGNETIC SPECTRUM

HARMFUL EFFECTS OF THE SUN’S ENERGY Sun Burn Heat Stroke Cataract Heat Rash Skin cancer Ages skin

CRUDE OIL crude oil is a mixture of complex hydrocarbon molecules and other organic compounds. Another name used for this material is petroleum, although that term also refers to products made from refined material itself.

CRUDE OIL Crude oil exists as a liquid found in various formations deep within the Earth’s crust. This liquid forms as a result of the decomposition of organic material that dates back millions of years, and are known as fossils.

Oil rig which is used in the extraction of crude oil.

Extraction of crude oil Extraction of crude oil. The lightest gases will come off fist and the heaviest substance (heavy oils) will come off last the others fall in the middle the substances are separated based on density (how heavy they are

USES OF CRUDE OIL

ENERGY EFFICIENCY Energy efficiency is not energy conservation. Energy efficiency is "using less energy to provide the same service". Energy efficiency is not energy conservation. Replacing an incandescent lamp with a compact fluorescent lamp (which uses much less energy to produce the same amount of light) is energy efficiency.

Energy usage/usable energy is also the work done ENERGY EFFICIENCY Energy usage/usable energy is also the work done

The efficiency of the hammer strike was 40%. ENERGY EFFICIENCY Efficiency Formula Questions: 1) A construction worker puts 20 J of energy in to one strike of his hammer on the head of a nail. The energy transferred to driving the nail in to the wood is 8.0 J. What is the efficiency of the construction worker's hammering? = 0.40 x 100% = 40% The efficiency of the hammer strike was 40%. Vibrations and heating of the nail are two possible reasons for the energy loss

ENERGY EFFICIENCY Energy is measured in joules. However, if you are given the mass and height of an object you can calculate the energy using the formula Mass X height X gravity (where gravity = 10)

ENERGY EFFICIENCY A ball of mass 0.2 kg is thrown vertically upwards and reaches a height of 15m. When the ball hits the ground it bounces to a height if 5m. Find: The energy of the ball when thrown up Mass (0.2) X height (15) X gravity (10) = 30 J b) The energy of the ball on rebound( when it hits ground and bounce) Mass (0.2) X height (5) X gravity (10) = 10 J c) The energy lost when ball hits the ground Energy input = useful energy + lost energy 30= 10 + x therefore the energy lost is 20 J 30-10= 20 J

ENERGY CONSERVATION Energy conservation is reducing or going without a service to save energy. For example: Turning off a light is energy conservation.