4.17

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4.16 (( no gallery))

4.16 understand the energy transfers involved in generating electricity using:

·         wind

·         water

·         geothermal resources

·         solar heating systems

·         solar cells

·         fossil fuels

·         nuclear power

	<<Srinakarin Hydro Dam, Kanchanaburi.avi>>

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Teacher Presentation.ppt Download this file

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Entrance Activity

<<Starter.ppt>>

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Starter.ppt Download this file

Power questions

PFY, p. 120

f) Power is the rate of doing work

Power ( in Watts) = Work done ( in Joules) / time ( in seconds)

g) 1 watt is a rate of working of one joule per second

13) P = E / t = 1000/5= 200 W

14)   Wd = F X D = 300 X 2 = 600 J

P = E/t = 600/6 = 100 W

16)   A) Wd = F X D = 3000 X 10 = 30000J

P= E/t = 30000/4 = 7500 W  

b) 7.5 Kilowatts

4.15

4.15 use the relationship between power, work done (energy transferred) and time taken:

          power = work done            P = Wd

                       time taken                    t

P = Wd / t

P = E / t

 

P = Power (Watts, W)

Wd = Work Done (Joules, J)

E = Energy Transferred (Joules, J)

t = Time (s)

4.14

4.14 describe power as the rate of transfer of energy or the rate of doing work

"Rate" just means "divided by time" (see Entrance Activity)

 

So

 

Power = Energy / Time

 

or

 

Power = Work done / Time

4.10

From: Matt Baker
Sent: 07 September 2011 14:00
To: Andrew Koomenjoe Nyaga; Arisara Amrapala; Boondaree Chang; Chrischawit Chomsoonthorn; Christopher Lo; Connor Blair Sailes; Frazer Allen Briggs; Huei-Yu Daniel Lo; Isabel Catriona McDonald; Kavin Supatravanij; Luke Michael Gebbie; Lydia Anna Foley; Morrakot Sae-Huang; Puchawin Borirackujarean; Qing Tang; Sanyam Grewal; Sebastien Grimm; Soo Hyun Lee; Tatiksha Singh; Usa Wongsanguan; Yanida Areekul; Yi-Lin Huang
Subject: 4.10 ((nogallery))

 

 

4.10

10 June 2011

11:51

·         4.10 understand that work done is equal to energy transferred

PFY p.112

Collins p. 91

 1.a) The work done ( measured in Joules) is equal to the force ( in newtons) multiplied by the distance moved (in metres).

b) 1 joule is the work done when a force of one newton moves through a distance of one metre ( in the direction of the force).

c) Work done = Energy transferred

2. Work done = Force X Distance

    Wd = 5N X 2m

          = 10 Joules

4.Work done = Force X Distance

   Wd = 500N X 40m

         = 20,000 Joules            

  The energy change is KE to GPE.

Collins p. 91

1.     400kg X 10 = 4000N

Work done = Force X Distance

50,000 = 4000N X Distance

50,000/4000 =Distance

12.5 m

 

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4.9

From: Matt Baker
Sent: 07 September 2011 13:42
To: Andrew Koomenjoe Nyaga; Arisara Amrapala; Boondaree Chang; Chrischawit Chomsoonthorn; Christopher Lo; Connor Blair Sailes; Frazer Allen Briggs; Huei-Yu Daniel Lo; Isabel Catriona McDonald; Kavin Supatravanij; Luke Michael Gebbie; Lydia Anna Foley; Morrakot Sae-Huang; Puchawin Borirackujarean; Qing Tang; Sanyam Grewal; Sebastien Grimm; Soo Hyun Lee; Tatiksha Singh; Usa Wongsanguan; Yanida Areekul; Yi-Lin Huang
Subject: 4.9

·         4.9 recall and use the relationship between work, force and distance moved in the direction of the force:

       work done = force × distance moved         

Wd = F × d

Work formula.ppt Download this file

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Plenary Questions

1. Thermal energy travels through the bottom of a pan by conduction. The energy is passed from one vibrating atom to the next. All metals are good conductors. Plastics, water and air are poor conductors (good insulators).

2. Convection currents can from when liquids and gases are heated. The cold fluid sinks and the hot fluid rises.

3. Energy can travel through empty space by infra-red rays, which can be reflected by mirros like light rays. Dull black surfaces are good radiators and good absorbers. Shiny, bright surfaces are poor radiators and poor absorbers.

4. A vacuum flask uses silvering to cut down heat transfer by radiation and uses a vacuum to cut down heat transfer by conduction and convection.

4.8

·         4.8 describe how insulation is used to reduce energy transfers from buildings and the human body

Task 1

·         Use this interactive animations to investigate how different insulation affects the rate of cooling of hot water

<<Cooling of hot water with insulation - interactive.swf>>

Task 2

·         Use these interactive animations to find out about the energy transfers in a house

	<<Types of energy transfers in a house - interactive.swf>>		<<Insulation in a house - % heat losses and savings.swf>>

Task 3

·         Test your knowledge with this quiz

<<Quiz - Types of energy transfers in a house.swf>>

Types of energy transfers in a house - interactive.swf Download this file

Quiz - Types of energy transfers in a house.swf Download this file

Insulation in a house - % heat losses and savings.swf Download this file

Cooling of hot water with insulation - interactive.swf Download this file

4.7

4.7

10 June 2011

11:42

·         4.7 describe the role of convection in everyday phenomena

Task 1

·         Try the animation
·         Extension: what is happening to the particles in the air? The particles moving faster, hitting each other. The space increases, the density decreases where the hot air rises up and the cold air take place moving down.

<<Convection in a room with a radiator.swf>>

Task 2

·         Why is Lee tired after cycling to the Sea in the morning? Because of the convection where the heat from the land rises up and the cold air from the sea move to the land , take place instead of the hot air.

·         Predict what will happen when Lee cycles home in the evening. He will be tiring since the wind is blowing in his way. This is because the land cools down and he sea is still hot so the convection works the opposite way from morning.

<<Lee cycles towards the sea ... and back worksheet.pdf>>

Lee cycles towards the sea ... and back worksheet.pdf Download this file

Convection in a room with a radiator.swf Download this file

Answers to

Entrance Activity for 4.7

Answers...
1. What is the most common heat transfer mechanism in solids?
Conduction

2. What is the most common heat transfer mechanism in liquids and gases?
Convection

3. What is the only heat transfer mechanism in a vacuum?
(Infra-red) Radiation

4. Why can't conduction happen in a vacuum?
There are no particles in a vacuum to transfer the vibrations

5. What happens to the space between the particles in a gas when you heat it?
The space between the particles increases

6. What happens to the density of a gas when you heat it?
It decreases because the space between the particles increases

7. Why can't convection happen in a solid?
In a solid the particles are fixed in position and are not free to move