4.6

Video - expansion of metal ball.flv Watch on Posterous

Particle model - conduction.swf Download this file

Cooking using Conduction, Convection and Radiation - interactive animation.swf Download this file

4.6 Energy transfer - Cooking

CONDUCTION: Heat moves directly from a hot surface to a cold surface


RADIATION:  Heat travels as rays through the air

4.5

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, including their representation by Sankey diagrams

 

 

1) Energy Value:

Wasted:             2*200=400J                                                                                                                                 

Heat-->Water: 5*200  1000J                                 

Sound E:            3*200=600J                                        

Check:           (400+600+1000=2000J)     

2)  Kettles efficiency: (Useful E/Total E )*100    

-->(1000/2000)*100à50%

3)  Energy converted into useful energy: Total E-Wasted E 

=150-(20+10)-->  150-30 --> 120J                                

4) Computer efficiency: (Useful E/Total E)*100-->(120/150)*100=0.8*100=80%

 

 

 

Plenary Questions 4.2 to 4.5

Plenary Questions.ppt Download this file

Plenary Questions 42 to 45.one Download this file

Energy Keywords

Eliza de Vries 10S

Types of energy

4.3 understand that energy is conserved

Energy is not made but it can be changed
the main source of energy 
=food
=which comes from plants 
=that photosynthesise
=which requires sunlight

Efficiency powerpoint

Efficiency.ppt Download this file

4.4 Efficiency

Efficiency = useful energy output/total energy input

Version 1

Efficiency = Useful E_out / Total E_in x 100

Useful E_out = Useful Energy out (J )

Total E_in = Total Energy In (J)

Efficiency = Efficiency ( % )

Version 2

Efficiency = Useful E_out / Total E_in

Useful E_out = Useful Energy out (J )

Total E_in = Total Energy In (J)

Efficiency = Efficiency (N/A; a pure number between 0 and 1)

4.2 describe energy transfers involving the following forms of energy:

thermal (heat), 

light, 

electrical, 

sound, 

kinetic, 

chemical potential, 

nuclear and potential (elastic and gravitational)

*Potential= stored energy 

Scientific facts to remember