Homework for next Tuesday
1. 4.6 to 4.8 Reading from Pearson. Note down 5 key facts from the text in your exercise books as 5 bullet points – I will check these at the beginning of next lesson. Stuck? Use Objectives 4.6 to 4.8 to guide you as to what you need to know.
2. Rate yourself using A/T/W/U against objectives 4.6 to 4.8 in the “End of lesson” column
4.6 to 4.8 Reading from Pearson
10 May 2012
14:41
4.2 to 4.5 Plenary Answers, Pearson p.132
10 May 2012
08:54
b.
Efficiency = Useful Eout / Total Ein x 100
Efficiency = 350 / 400 x 100
Efficiency = 88%
a. It is transferred to thermal and sound energy
4.2 to 4.5 Plenary Questions, Pearson p.132
10 May 2012
08:54
4.5
10 June 2011
11:42
· 4.5 describe a variety of everyday and scientific devices and situations, explaining the fate of the input energy in terms of the above relationship (see 4.4), including their representation by Sankey diagrams
4.5 plenary questions and answers
10 June 2011
11:42
Answers
Kettle
10 squares = 2000J/s therefore 1 square = 200J/s
Wasted Heat = 2 squares = 400J/s
Useful Heat = 5 squares = 1000J/s
Wasted sound = 3 squares = 600J/s
Efficiency = Useful Eout / Total Ein x 100
Efficiency = 1000 / 2000 x 100
Efficiency = 50%
Computer
Conservation of energy so…
Total Ein = Total Eout
150J = 20 + 10 + Useful Eout
Useful Eout = 120J/s
Efficiency = Useful Eout / Total Ein x 100
Efficiency = 120 / 150 x 100
Efficiency = 80%
4.4
10 June 2011
11:42
· 4.4 know and use the relationship:
efficiency = Useful Eout / Total Ein
Version 1
Efficiency = Useful Eout / Total Ein x 100
Useful Eout = useful energy output (J)
Total Ein = total energy input (J)
Efficiency = Efficiency (%)
Version 2
Efficiency = Useful Eout / Total Ein
Useful Eout = useful energy output (J)
Total Ein = total energy input (J)
Efficiency = Efficiency (no units; a number between 0 and 1)
4.4 Plenary questions
10 June 2011
11:42
<<Efficiency.ppt>>
4.4 starter
10 June 2011
11:42
<<% efficiency energy.swf>>
4.3
10 June 2011
11:42
• 4.3 understand that energy is conserved
<<Energy input; energy output worksheets.pdf>>
Example answer
4.2 starter
10 June 2011
15:32
Tell the person next to you…
1. What are the 9 types of energy?
(Note: "solar", "wind", etc are NOT types of energy - they are energy resources!)
























