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Energy Grade 7

Energy Grade 7. Heat energy. Two main sources of energy. Non-renewable sources: Fossil fuels Wood Coal Oil Gas Description: Will not be available for ever we are running short of these resources. Renewable sources Nature provide these Sun Wind Water Description:

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Energy Grade 7

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  1. Energy Grade 7 Heat energy

  2. Two main sources of energy • Non-renewable sources: • Fossil fuels • Wood • Coal • Oil • Gas Description: Will not be available for ever we are running short of these resources • Renewable sources • Nature provide these • Sun • Wind • Water Description: Will be in nature at all times but in different quantities at times.

  3. Fossil fuels They are made from the remains of plants and animals that died many millions of years ago.

  4. HEAT ENERGY What is heat • Objects feel hot or cold because they contain heat • Hot objects contain more heat • Cold objects contain less heat • This is an indication of the amount of energy that an object has. • More heat means more energy, which indicates that the particles are moving faster • Heat causes the temperature of an object to rise • We can measure the heat with a thermometer. • The temperature is then indicated in 0C or 0F • The 0C is the unit we use to indicate the heat the object has • This is a method of measuring the energy that object has or the ability of the particles to move around What happens to the temperature of water when we heat it on a stove? What is temperature

  5. Transfer of heat energy Conduction • Happens in a solid • Particles at warm end has more energy • Particles at cold end has less energy • Energy is transferred from warm particles to the cold particle • Can be explained with metal rod in burning candle

  6. Transfer of heat energy Convection • Happens in a liquid or a gas • Particles at warm end rises • Particles at cold end decent • Energy is transferred from warm particles to the cold particle • Can be explained with coloured water in glass beaker on burner • This causes convection currents and convection rain

  7. Transfer of heat energy Radiation • Happens in a medium without contact • Heat from the sun takes 8 minutes to reach earth after traveling 150 million km • Heat travels in the form of waves • The heat will be absorbed by conductors • Heat will not be absorbed by insulators • This causes the inside of a car to heat up in the sun

  8. Revision page Give one word for the following: 1.1. contains nutrients to make the plants grow better. 1.2. formed under ground or under the sea million of years ago from buried plants and animals. 1.3. an instrument for measuring temperature Explain the difference between: 2.1. renewable and non-renewable energy sources 2.2. heat and temperature 2.3. conduction and convection 2.4. conductors and insulators Report in your group on the following issue: The burning of fossil fuels and the impact it has on the environment

  9. Brain-Teasers How does the use of electricity pollutes the environment? What happens to our marine life when there is an oil spill? Why do some scientist concider nuclear energy to be safe and others not? What does it mean to be energy-efficient? Would you say that South Africa is energy-efficient? Give reasons. Why do we not have any hydro-electric power plants in South Africa?

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