Energy, Work And Power
Overview
Nothing happens without energy being shifted from one store to another. A falling diver, a glowing bulb, a sprinting athlete, a charging phone: each is energy moving from where it was kept to somewhere new. The grand rule that ties it all together is that the total never changes, only its form and location.
In this lesson you will name the energy stores, describe how energy is transferred by forces, currents, heating and waves, and use the principle of conservation of energy to read flow and Sankey diagrams. You will also calculate kinetic energy, gravitational potential energy, work and power, always showing the equation, the substitution and the answer with units.
Objectives
- State that energy may be stored as kinetic, gravitational potential, chemical, elastic (strain), nuclear, electrostatic and internal (thermal)
- Describe how energy is transferred between stores during events and processes, including examples of transfer by forces (mechanical work done), electrical currents (electrical work done), heating, and by electromagnetic, sound and other waves
- Know the principle of the conservation of energy and apply this principle to simple examples including the interpretation of simple flow diagrams
- [Supplement] Recall and use the equation for kinetic energy Eₖ = ½mv²
- [Supplement] Recall and use the equation for the change in gravitational potential energy ∆E = mg∆h p
- [Supplement] Know the principle of the conservation of energy and apply this principle to complex examples involving multiple stages, including the interpretation of Sankey diagrams
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Energy, Work And Power. 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.
- Which is NOT an energy store? A. chemical B. heating C. elastic (strain) D. gravitational potential Answer: B
- A 2 kg ball moves at 10 m/s. Its kinetic energy is A. 10 J B. 20 J C. 100 J D. 200 J Answer: C
- A 5 kg mass is lifted 4 m (g = 9.8 N/kg). The gain in gravitational potential energy is A. 20 J B. 49 J C. 196 J D. 200 J Answer: C
- A force of 20 N moves a box 3 m in the direction of the force. The work done is A. 6.7 J B. 23 J C. 60 J D. 600 J Answer: C
- A motor does 800 J of work in 4 s. Its power output is A. 0.005 W B. 200 W C. 800 W D. 3200 W Answer: B
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Recommended Books
Practice Mock Questions
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