Energy, Work And Power
Aperçu
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.
Objectifs
- 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
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Carte mentale
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Évaluation de la leçon
Félicitations, vous avez terminé la leçon sur Energy, Work And Power. Maintenant que vous avez exploré le concepts et idées clés, il est temps de mettre vos connaissances à l'épreuve. 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.
- 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
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Livres recommandés
Pour aller plus loin, ressources libres
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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
Conservative Forces and Potential Energy
Work is done by a force, and some forces, such as weight, have special characteristics. A conservative force is one, like the gravitational force, for which work done by or against it depends only on the starting and ending points of a motion and not on the path taken. We can define a potential ener
"College Physics: Conservative Forces and Potential 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/7-4-conservative-forces-and-potential-energy. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
Publiées par d'autres organisations sous licence libre, créditées comme elles le demandent. Les liens ouvrent leurs sites.
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