Energy, Work And Power (continued 1)
Aperçu
Work is how energy gets moved around, and power is how fast that happens. But the bigger story is where our energy comes from in the first place: fossil fuels, the wind, the tides, the Sun and the atomic nucleus. Each source has its own balance of benefits and costs.
In this lesson you will link work done to energy transferred with \(W=Fd\), survey the major energy resources and weigh up their advantages and disadvantages, and calculate the efficiency of an energy transfer. You will also see why almost all our energy traces back to the Sun.
Objectifs
- Understand that mechanical or electrical work done is equal to the energy transferred
- Recall and use the equation for mechanical working W = Fd = ∆E
- Describe how useful energy may be obtained, or electrical power generated, from: (a) chemical energy stored in fossil fuels (b) chemical energy stored in biofuels (c) water, including the energy stored in waves, in tides and in water behind hydroelectric dams (d) geothermal resources (e) nuclear fuel (f) light from the Sun to generate electrical power (solar cells) (g) infrared and other electromagnetic waves from the Sun to heat water (solar panels) and be the source of wind energy including references to a boiler, turbine and generator where they are used
- Describe advantages and disadvantages of each method in terms of renewability, availability, reliability, scale and environmental impact
- Understand, qualitatively, the concept of efficiency of energy transfer
- [Supplement] Know that radiation from the Sun is the main source of energy for all our energy resources except geothermal, nuclear and tidal
- [Supplement] Know that energy is released by nuclear fusion in the Sun
- [Supplement] Know that research is being carried out to investigate how energy released by nuclear fusion can be used to produce electrical energy on a large scale
- [Supplement] Define efficiency as: (a) (useful energy output) (%) efficiency = (× 100%) (total energy input) (b) (useful power output) (%) efficiency = (× 100%) (total power input) recall and use these equations
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Évaluation de la leçon
Félicitations, vous avez terminé la leçon sur Energy, Work And Power (continued 1). Maintenant que vous avez exploré le concepts et idées clés, il est temps de mettre vos connaissances à lépreuve. Cette section propose une variété de pratiques des questions conçues pour renforcer votre compréhension et vous aider à évaluer votre compréhension de la matière.
Vous rencontrerez un mélange de types de questions, y compris des questions à choix multiple, des questions à réponse courte et des questions de rédaction. Chaque question est soigneusement conçue pour évaluer différents aspects de vos connaissances et de vos compétences en pensée critique.
Utilisez cette section d'évaluation comme une occasion de renforcer votre compréhension du sujet et d'identifier les domaines où vous pourriez avoir besoin d'étudier davantage. Ne soyez pas découragé par les défis que vous rencontrez ; considérez-les plutôt comme des opportunités de croissance et d'amélioration.
- A force of 20 N moves an object 5 m in the direction of the force. The work done is: A. 4 J B. 25 J C. 100 J D. 200 J Answer: C
- A machine takes in 800 J and gives 600 J of useful output. Its efficiency is: A. 25% B. 75% C. 133% D. 200 J Answer: B
- Which energy resource is NOT ultimately driven by the Sun? A. wind B. waves C. geothermal D. biofuel Answer: C
- The Sun releases its energy mainly by: A. burning hydrogen as a fuel B. nuclear fusion C. nuclear fission D. chemical reactions Answer: B
- Which is a renewable energy resource? A. coal B. natural gas C. nuclear fuel D. tidal Answer: D
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Section de manuel
Conservation of Energy
Energy, as we have noted, is conserved, making it one of the most important physical quantities in nature. The law of conservation of energy can be stated as follows: Total energy is constant in any process. It may change in form or be transferred from one system to another, but the total remains th
"College Physics: Conservation of Energy" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/7-6-conservation-of-energy. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
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Section de manuel
Fusion
While basking in the warmth of the summer sun, a student reads of the latest breakthrough in achieving sustained thermonuclear power and vaguely recalls hearing about the cold fusion controversy. The three are connected. The Sun’s energy is produced by nuclear fusion (see Figure 32.13 ). Thermonucle
"College Physics: Fusion" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/32-5-fusion. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
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