Energy, Work And Power (continued 1)
Overview
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.
Objectives
- 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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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Energy, Work And Power (continued 1). Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- 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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Recommended Books
Further learning from open sources
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Textbook section
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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Textbook section
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
Published by other organisations under open licences, credited as they ask. Links open their websites.
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