Energy Resources
Muhtasari
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. Every statement in this topic is set for both tiers, so nothing here is anybody else's problem.
Malengo
- 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.
- When a fuel is used, some energy is transferred to the surroundings. Some fuels are more efficient than others.
- 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.
- 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.
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Maelezo ya Somo
Dokezo Kamili la Somo Linapatikana kwenye Programu ya Green Bridge
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Tathmini ya Somo
Hongera kwa kukamilisha somo la Energy Resources. Sasa kwa kuwa umechunguza dhana na mawazo muhimu, ni wakati wa kuweka ujuzi wako kwa mtihani. Sehemu hii inatoa mazoezi mbalimbali maswali yaliyoundwa ili kuimarisha uelewaji wako na kukusaidia kupima ufahamu wako wa nyenzo.
Utakutana na mchanganyiko wa aina mbalimbali za maswali, ikiwemo maswali ya kuchagua jibu sahihi, maswali ya majibu mafupi, na maswali ya insha. Kila swali limebuniwa kwa umakini ili kupima vipengele tofauti vya maarifa yako na ujuzi wa kufikiri kwa makini.
Tumia sehemu hii ya tathmini kama fursa ya kuimarisha uelewa wako wa mada na kubaini maeneo yoyote ambapo unaweza kuhitaji kusoma zaidi. Usikatishwe tamaa na changamoto zozote utakazokutana nazo; badala yake, zitazame kama fursa za kukua na kuboresha.
- Which of these is a renewable energy source? A. Coal B. Natural gas C. Geothermal D. Uranium Answer: C
- 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
- 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
- Hydrogen holds about 120 MJ per kilogram and diesel about 45 MJ per kilogram. Why is diesel still chosen for a standby supply? 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 waste no energy D. Hydrogen cannot be burnt in an engine Answer: B
- A device is supplied with 600 J of energy and transfers 450 J usefully. What happens to the other 150 J? A. It is destroyed B. It is stored in a less useful way, warming the surroundings C. It is returned to the supply D. It becomes extra useful energy later Answer: B
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