Today we looked at how a thermos can keep stuff hot or cold. We noted the shiny inside of the thermos and how it would reflect radiant heat. We also noted the vacuum in the double lining, and how that would stop convection and conduction. Convection isn’t much of a problem because it is hard to establish a current in this small a space, but still possible…Here’s a website with the information again http://home.howstuffworks.com/thermos.htm
Have just downloaded and printed the Standard, the old exam papers and the marking schedules and exemplars for astronomy – you may want to do something similar
http://www.nzqa.govt.nz/ncea/assessment/view-detailed.do?standardNumber=90192
Nothing much to say after that! Unit test, 2 credits, see you period 5
That unit standard seems to be going okay – though I have only marked about four of them! But I found the other one on physics, so lets do that on Friday. Any objections, voice them…. The homework was page 87 questions one and two (from memory) Could have been page 81? But it is the first couple of questions on electricity in your green book. Mark your own, the answers are in the back of the book. Any problems let me know, here or at class.
If your brain is anything like mine you are starting to go into a kind of daze now when I put equations on the board. When I was at school I never really understood what the equations meant or when I was supposed to use them… What I did know was that distance was measured in metres, time was measured in seconds and speed (or velocity) was measured in metres/second. So you could say I knew the units of what I was trying to find out. So I would find an equation that gave me the units of what I was looking for, and see if I could combine the numbers I got in the question using that equation. Its a pretty cack-handed way of going about things now I look at it, but it was successful enough.Learning that “I” stood for current, which was measured in Amps would have been a huge leap forward when I was 15…Hope you are all having a lovely evening, remember to study for the car test 
You found out about how voltage gets used up round a series circuit, and how parallel circuits are like magic, and all are little independent circuits… Next week we have a unit standard test on Tuesday – I think it is contextual and on cars so we have to do some Weird Stuff on Monday. Congrats to Mos, Josh and Luke who got a 2 credit unit standard done today while the rest of you caught up to them… We made it! First week down! Weekend! Hooray!!
Its pretty disappointing how much time you guys waste during practicals – now we have to use another period getting the voltmeter readings.
You should have found the ammeter readings are the same the whole way round the circuit, and as Reggie pointed out that is because they are measuring the number of electrons flowing, which should be the same as electrons don’t get used up!!
Tomorrow the voltmeters, and you should find quite a different pattern, which makes sense as the voltmeter measures the energy in the electrons, which should change as they go round the circuit…
No homework to hand in, but have a read of pg 83 and 84.
You have now been told what electricity is and you also know what ammeters and voltmeters measure. Tomorrow we will use the gear…
You have a worksheet for today’s homework which I will take in and mark. You also have your magic sheet of information to glue into your books – remember I am not giving you another one of the magic sheet… If you lose it, your loss!
Last two equations today – work is calculating the effort required to do something, and power is looking at the relationship of work and time. The faster you do something the more power it takes, but the actual work done is the same.
Make sure you know this is a SCIENCE use of the words work and power… don’t think the words mean the same thing in the big bad scarey world.
Homework was questions one and two from page 80 and 81.
So today there were another couple of equations, both of them for calculating the amount of energy something has. The units are Joules (J) Kinetic energy or E(k) is working out how much energy a moving object has. Potential energy is how much energy is stored in a high object – like the energy in the water of a dam, or something lifted off the earth.Potential energy is E(p)=m.g.h So the higher you lift something the more energy it has. The larger the object you lift the more energy it has. g is for gravity, which remains a constant on this earth and you will be told g=10m.s-2. Try it with some simple numbers eg m=4g, g=10m.s-2, and h=12m, and then double the mass to 8g. Try doubling the height to 24m… When they went to the moon gravity was less. But imagine (or calculate) the effect of going to Jupiter where gravity =40m.s-2 The homework was to finish the question given in class and do Question Four of page 81 in your green book…The class question was: A metal weight (2700g) in the gymnasium was left on a shelf 2m above the floor. It falls. It takes 0.8secs to fall (me bad, thanks for noticing Gavin)How much energy did it have on the shelf?How fast was it going when it hit the ground?What was its acceleration?With what force did it hit the ground?