Posterous theme by Cory Watilo

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

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4.6 to 4.8 Reading from Pearson

10 May 2012

14:41

(download)

 

 

4.2 to 4.5 Plenary Answers, Pearson p.132

10 May 2012

08:54

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b.

Efficiency = Useful Eout / Total Ein x 100

Efficiency = 350 / 400 x 100

Efficiency = 88%

 

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a.               It is transferred to thermal and sound energy

 

 

4.2 to 4.5 Plenary Questions, Pearson p.132

10 May 2012

08:54

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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

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4.5 plenary questions and answers

10 June 2011

11:42

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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>>

Click here to download:
Efficiency.ppt (214 KB)
(download)

 

 

4.4 starter

10 June 2011

11:42

<<% efficiency energy.swf>>

(download)

 

 

4.3

10 June 2011

11:42

•        4.3 understand that energy is conserved

<<Energy input; energy output worksheets.pdf>>

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Example answer

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Click here to download:
Energy input; energy output worksheets.pdf (311 KB)
(download)

 

 

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!)