1.12
Tuesday, July 06, 2010 3:04 PM· 1.12 add forces that act along a line
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Tuesday 27 September 2011
Wednesday 21 September 2011
PFY p.120
Answers
f) Power is the rate of doing work
Power (In Watts) = work done (in Joules) / time (in seconds)
g) 1 watt is the rate of working at one Joule per second
13. P = Wd/t = 1000/5 = 200W
14. P = Wd/t
Work done = force x distance = 300 x 2
P = 600/6 = 100W
15. P = Wd/t
Work done = f x d = 3000 x 10
P = 30000/4 = a) 7500W => b) 7.5kW
4.16
4.16 10 June 2011 11:55
· 4.16 understand the energy transfers involved in generating electricity using:
· wind
· water
· geothermal resources
· solar heating systems
· solar cells
· fossil fuels
· nuclear power
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· 4.16 understand the energy transfers involved in generating electricity using:
· wind
· water
· geothermal resources
· solar heating systems
· solar cells
· fossil fuels
· nuclear power
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Answers
Answers 19 August 2011 17:30
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Entrance Activity
Entrance Activity 19 August 2011 17:44 Tell the person next to you...
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P4 IGCSE Physics Student Objectives
Dear Y11 Physicists, Thanks to Sanyam for spotting a typo in the paper versions of Obj 4.4 of the attached. Corrected version attached. [cid:image001.jpg@01CC7862.AD9DA660] Note that this formula is correct (gives answer as a number between 1 and 0) and the same formula x 100 is also correct (gives answer as a %) Cheers, Mr B P4 IGCSE Physics Student Objectives 10 June 2011 11:20 > Inserted from: >
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Power questions
Power questions 19 August 2011 17:30 PFY, p. 120 [cid:image001.png@01CC7861.A7A2D8D0] [cid:image002.png@01CC7861.A7A2D8D0] Answers: f) Power is the rate of doing work Power (In Watts) = work done (in Joules) / time (in seconds) g) 1 watt is the rate of working at one Joule per second 13. P = Wd/t = 1000/5 = 200W 14. P = Wd/t Work done = force x distance = 300 x 2 P = 600/6 = 100W 15. P = Wd/t Work done = f x d = 3000 x 10 P = 30000/4 = a) 7500W => b) 7.5kW
4.15
4.15 10 June 2011 11:54
· 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)
· 4.15 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 10 June 2011 11:53
· 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
· 4.14 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
4.14 Entrance Activity Answers
4.14 Entrance Activity Answers 19 August 2011 17:17 Tell the person next to you...
· You can run up the stairs in the Science block in 30 seconds.
· Mr. Roff can run up the stairs in the Science block in 20 seconds.
· Who is the most powerful? Why?
· Mr Roff. He does more work running up the stairs (because has a higher weight) in a shorted time so he is more powerful
· It takes 2 minutes to fill the 20 litre sinks in this room with water.
· How fast is the sink filling?
· 10 litres/min
· At what rate is the sink filling?
· 10 litres/min
· How long would it take to fill a 10 litre sink?
· 1 min
· You can run up the stairs in the Science block in 30 seconds.
· Mr. Roff can run up the stairs in the Science block in 20 seconds.
· Who is the most powerful? Why?
· Mr Roff. He does more work running up the stairs (because has a higher weight) in a shorted time so he is more powerful
· It takes 2 minutes to fill the 20 litre sinks in this room with water.
· How fast is the sink filling?
· 10 litres/min
· At what rate is the sink filling?
· 10 litres/min
· How long would it take to fill a 10 litre sink?
· 1 min
Wednesday 14 September 2011
CoE questions
CoE questions 19 August 2011 17:00 PFY p.121 [cid:image001.png@01CC72E7.51FD2C20] Collins, p.91 [cid:image002.png@01CC72E7.51FD2C20] Answers PFY p121 a) W = m x g --> W = 50 x 10 = 500N CORRECT
b) GPE = W x h --> 500 x 4 = 2000J CORRECT
c) Total E at Start = Total E at End --> 2000J = KE + 0 --> 2000J CORRECT Answers PFY p91 a) GPE = mgh --> 35 x 10 x 30 = 10500J CORRECT
b) GPE at top = KE at bottom --> KE = 1/2 mv^2 --> v = sqr(10500/(35/2)) = 24.5 m/s CORRECT
c) There is friction from the snow and the sledge, which converts the KE into heat energy; therefore not all of the GPE is transferred to KE as that energy is 'wasted' CORRECT
b) GPE = W x h --> 500 x 4 = 2000J CORRECT
c) Total E at Start = Total E at End --> 2000J = KE + 0 --> 2000J CORRECT Answers PFY p91 a) GPE = mgh --> 35 x 10 x 30 = 10500J CORRECT
b) GPE at top = KE at bottom --> KE = 1/2 mv^2 --> v = sqr(10500/(35/2)) = 24.5 m/s CORRECT
c) There is friction from the snow and the sledge, which converts the KE into heat energy; therefore not all of the GPE is transferred to KE as that energy is 'wasted' CORRECT
4.13
4.13 10 June 2011 11:53
· 4.13 understand how conservation of energy produces a link between gravitational potential energy, kinetic energy and work
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· 4.13 understand how conservation of energy produces a link between gravitational potential energy, kinetic energy and work
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Monday 12 September 2011
Correct Answer for Topic Keywords
Test on all keywords next lesson. Credits available for excellent scores on test!
Option 1: Visual learners – Test yourself.o Cover up the keywords, read the definitions, write down the keyword, check the spelling. Option 2: Auditory learners – Test each other.
o Ask your friends or a member of your family to read out the definitions. You answer by giving them the answer and the correct spelling. Option 3: Kinaesthetic learners – Online Games
o Play keyword tests @
o http://www.patana.ac.th/LearningObjects/%7B6B1B5FCC-5C7F-4006-879F-8AB0242337...
o http://www.patana.ac.th/LearningObjects/%7B13E1C74F-83AE-48D4-85EF-A14ADC441F...
o http://www.patana.ac.th/LearningObjects/%7B77B26252-136C-4160-9BAD-A34666E3DD...
o Don’t forget to do the crossword to practice your spelling!
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Thursday 8 September 2011
4.12
4.12 10 June 2011 11:52
· 4.12 recall and use the relationship: kinetic energy = ½ × mass × speed2 KE = ½ × m × v2
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· 4.12 recall and use the relationship: kinetic energy = ½ × mass × speed2 KE = ½ × m × v2
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4.11
4.11 10 June 2011 11:52
· 4.11 recall and use the relationship: gravitational potential energy = mass × g × height GPE = m × g × h
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· 4.11 recall and use the relationship: gravitational potential energy = mass × g × height GPE = m × g × h
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Wednesday 7 September 2011
Starter - answers
Starter - answers 19 August 2011 16:11 Tell the person next to you...
· Imagine pushing a king sized bed from one side of the classroom to the other
· Would it make you feel tired?
o Yup!
· Would you have to work hard to push it?
o Yup!
· What could you change so you have to do less work pushing?
o Anything that decreases the force needed (reduce friction by putting wheels on it, ice under it, etc)
o Anything that decreases the distance travelled (only push it half way!, etc)
o So the formula for work must contain force and distance Created with Microsoft OneNote 2010
One place for all your notes and information
· Imagine pushing a king sized bed from one side of the classroom to the other
· Would it make you feel tired?
o Yup!
· Would you have to work hard to push it?
o Yup!
· What could you change so you have to do less work pushing?
o Anything that decreases the force needed (reduce friction by putting wheels on it, ice under it, etc)
o Anything that decreases the distance travelled (only push it half way!, etc)
o So the formula for work must contain force and distance Created with Microsoft OneNote 2010
One place for all your notes and information
4.10
4.10 10 June 2011 11:51
· 4.10 understand that work done is equal to energy transferred PFY p.112 [cid:image001.png@01CC6D66.70900440] [cid:image002.png@01CC6D66.70900440] [cid:image003.png@01CC6D66.70900440] Collins p. 91 [cid:image004.png@01CC6D66.70900440] 
· 4.10 understand that work done is equal to energy transferred PFY p.112 [cid:image001.png@01CC6D66.70900440] [cid:image002.png@01CC6D66.70900440] [cid:image003.png@01CC6D66.70900440] Collins p. 91 [cid:image004.png@01CC6D66.70900440]
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