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# 2.2 Describing energy

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Energy transformations, energy block diagrams, sankey diagrams

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### 2.2 Describing energy

1. 1. 10 October 2010<br />2.2 Describing energy<br />Jenny is a trainee engineer working for an aerospace company. She is working with other engineers to design a more efficient engine for aeroplanes. They want the engine to transform as much energy as possible into useful forms and to reduce the amount of energy that is wasted.<br />Which types of energy given out by the engine are wasted?<br />
2. 2. Investigating energy<br />You need to describe energy changes that take place in everyday situations<br />
3. 3. What energy does the ball have?<br />Ball on a bench<br />Falling ball<br />Ball rebounding<br />
4. 4. We use energy block diagrams to understand how energy is transformed<br />Electrical energy used for radio, lights, recharging battery etc<br />Tracking transformations<br />Chemical energy from burning fuel<br />Kinetic energy used to move the lorry<br />Wasted thermal and sound energy<br />
5. 5. Activity A: Draw a block diagram to show the energy transformations for someone using a hair drier<br />
6. 6. Activity A: Draw a block diagram to show the energy transformations for someone using a hair drier<br />Heat from heater<br />Electrical energy from mains<br />Kinetic energy from fan<br />Sound of fan<br />
7. 7. Useful versus wasteful<br />It is sometimes good to know exactly how much energy is being used<br />We use a sankey diagram to show this<br />The width of the arrows shows the amount of energy<br />
8. 8. Electrical energy used for radio, lights,<br />Recharging battery etc. 20 000J<br />Wasted thermal<br />and sound energy<br />100 000 J<br />Chemical energy from<br />Burning fuel 200 000 J<br />Kinetic energy to move <br />the lorry 80 000 J<br />
9. 9. Assessment activity 2.2<br />You are working for a leading IT company. Your manager wants you to look into energy efficient computers. To start you investigate the energy used by one of the company’s existing computers.<br />1. State in words the types of energy involved when the computer is in use P1<br />2. Draw a block diagram to show the energy transformations M1<br />3. 350 J of electrical energy is supplied to the computer. In the process 65 J is used to generate light energy, 190 J is transformed into heat and 95 J into sound. Draw a Sankey diagram to show the energy transfers.<br />