1. First in come to me Come to me Quick quick... there’s prizes... And pixies... And other nice stuff... Not really but you do get to be in charge of the game

2. Learning Objectives ‘Lost’ Energy To understand that energy is never destroyed To be able to understand Sankey Diagrams 21 November 2011 Key Words – 1.Sankey Diagram 2.Energy 3.Transfer 4.Convert Starter question How much energy efficient do you think a car engine is? Guess how much of the chemical energy is turned into kinetic energy 5 Minute Task

3. Lesson Plan Learning Objectives What is efficiency? Calculation practice Sankey Diagrams Practice drawing a Sankey Diagram What is work? How do you calculate it? How does power relate to work?

4. Calculating efficiency Sounds scary, but really it is not! What do you think a really efficient thing is? Tell your friend next to you. Getting a lot out of what you put in is “high efficiency” Now sums Efficiency = Useful energy out Energy in

5. Calculating An engine takes in 100 Joules of energy but only 30 Joules of movement is made. A light bulb takes in 50 J of electrical energy but gives out 5 J of light. An power station takes in 3 MJ of chemical energy and makes 1 MJ of electrical energy.

6. Sankey Diagrams

7. Work and Power Read pages 56-59 in your Physics for Cambridge IGCSE textbook Make notes on any key points Complete the questions on p 57 & 59 Copy the equation for power and substitute in the equation for work Read and attempt the exam-style questions on pages 60-61.

8. Learning Outcomes All of you should … –Know that energy is never lost and understand where it goes and be able to calculate work and power Most of you should… –Be able to describe what work and power are Some of you should… –Be able to assess efficiencies, work and power and make comments on them