Physics - 9203 OxfordAQA

Energy Resources

Gbogbo ọrọ náà

Somebody, somewhere, had to decide what would be burnt or turned or heated to light the room you are sitting in. That decision was not made by a physicist alone. It weighed how much a kilogram of the stuff carries, whether it can be kept safely in a tank behind a building, what it does to the air of the town, what it leaves behind when the plant is dismantled in forty years, and whether it will still be there for your grandchildren. Every one of those questions has a physics answer underneath a political argument, and this lesson is about the physics.

You will learn to read a fuel as a store with a price tag: so many megajoules in every kilogram, kept in a particular way, dangerous in a particular way. You will work out how much of a fuel a job actually needs once you allow for the share that goes into warming the neighbourhood instead of doing the job, and you will see why two stoves burning different fuels can need six times as much mass for the same hot pot. Then you will step up to the national scale: what separates a renewable source from one that runs out, why renewable and harmless are not the same word, and what wave, solar and geothermal schemes are genuinely good and genuinely bad at.

Ebumnobi

  1. Fuels are a useful store of energy; different fuels are suitable for different situations and are selected according to a range of factors, such as ease of storage, energy content and safety.
  2. When a fuel is used, some energy is transferred to the surroundings. Some fuels are more efficient than others.
  3. There is a range of energy sources used on a national and global scale. Their use has implications for society in terms of factors including renewability and the environmental impacts of extraction, use and disposal.
  4. A range of technologies have been developed to provide energy in a renewable way, such as wave power, solar power and geothermal power. Students should be aware of these and other examples and be able to identify advantages and drawbacks with their use.

Maapụ uche

E seela isiokwu a ka ị hụ otu echiche si ejikọta.

Mepee maapụ uche na ngwa

Akwụkwọ Ọmụmụ

A hospital on the edge of a town needs a generator that will start at three in the morning, on the day the grid fails, and keep running for two days without anyone visiting it. Physics will tell you that hydrogen carries more than twice as much energy per kilogram as diesel does. Nobody builds hospital generators that run on hydrogen. The reason has nothing to do with the size of that number and everything to do with the other questions: what would the fuel have to be kept in, how big would the vessel be, and what happens if it leaks into a corridor.

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Nnyocha Ọmụmụ

Ekele diri gi maka imecha ihe karịrị na Energy Resources. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.

Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.

Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.

  1. Which of these is a renewable energy source? A. Coal B. Natural gas C. Geothermal D. Uranium Answer: C
  2. A fuel has an energy content of 40 MJ per kilogram. A burner using it is 30% efficient. How much useful energy is delivered by burning 2.0 kg of the fuel? A. 12 MJ B. 24 MJ C. 80 MJ D. 240 MJ Answer: B
  3. A hospital must have electricity all night. What is the main drawback of supplying it from solar panels alone? A. Solar panels release sulfur dioxide B. The output falls to zero at night, so storage or a second source is needed C. Solar panels can only be built where the rock below is hot D. Solar panels destroy the mudflats in an estuary Answer: B
  4. Hydrogen holds about 120 MJ per kilogram and diesel about 45 MJ per kilogram. Why is diesel still chosen for a standby generator? A. Burning diesel releases no carbon dioxide B. Diesel is a liquid at ordinary pressure, so far more energy fits into a plain tank C. Diesel engines are 100% efficient D. Hydrogen cannot be burnt in an engine Answer: B
  5. Which renewable source gives an output that can be predicted years in advance? A. Wind B. Solar C. Tidal D. Wave Answer: C

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