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Unit 8 GRAVITY, FRICTION AND MAGNETISM

A lot of things in the universe can be measured, but people want to know why they are that size. We know the mass of a quark and the charge on an electron. These are constants. It turns out that these numbers have to be exactly what they are, because if they were different we would not be here. You, me and the physicists, we’re part of the universe. We have to be here to make physics, so physics has to describe a universe where there can be people. Gravity is another problem for physics - because it is everywhere and acts on everything, including space itself. It’s different from other forces like electricity or radiation, because you can’t stop it or turn it off.

Modern physicists still look mostly at things we can’t see. (They think gravity might happen because of something no-one has ever detected called the Higg’s boson.) Either very small things in quantum physics or very big things like galaxies. Putting them together is the main problem of modern physics. The universe and space and time described by Einstein and the fuzzy fast-moving little sub-atomic particles and small things that might make them up. If you want to know how the universe began - with a tiny size but very big mass, then you need a theory that fits both together. At the moment, the theory suggests that the things we can see – stars and planets etc. make up only 5% of the universe. The rest is 25% “dark matter” and 70% “dark energy”.

 

 

Unit 9 SIMPLE MACHINES

Simple Machines: lyrics

These simple machines share a plan of attack:

A broom, a crowbar and a baseball bat

And so does a hammer when it's pounding a tack

And the fork in your hand when you're having a snack

Tell me the name of this machine

The one that gives me so much leverage?

It's a LEVER

You can ride up a ramp or slide down a slide

Take a trip to the top of a roller coaster ride

You'll be using this tool with every stair that you climb

Go up a ladder, if you're so inclined!

Tell me the name of this machine

The one that makes going uphill so easy?

It's an INCLINED PLANE

With an axe or a knife you can split into two

Any number of things that a razor can't do

And a sword's what to choose when you're challenged to duel

You can split, trim or cut with this versatile tool

Tell me the name of this machine

The one that helps split things into two?

It's a WEDGE

With the twist of a lid I could see right away

That the ridge on the jar is what made the lid stay

And the base of a light bulb has angular ribs

Which thread themselves tight when you twist the bulb in

Tell me the name of this machine

The one that holds things tightly together?

It's a SCREW

Unit 10 COMPLEX MACHINES

Bicycle

Recording 1

Now, count up the parts on your drawing. Did you include wheels? A handlebar? A saddle? A chain? A crossbar? Pedals? Did your bike have at least five parts? And could it work? Now for the difference between the men’s drawings of bicycle and women’s: female drawings often include a person riding the bike, men’s drawings don’t usually include a person. This is a clear indication that women think people are important. Men, on the other hand, are more interested in getting the machine right.



Recording 2

P = Presenter W1 = 1st woman

M1 = 1st man W2 = 2nd woman

P: Here are some comments from men and women who did the test.

W1: Hmmm. Well, I only got four parts right. How many did you get right?

M1: I only got four. How many did you get?

W2: I’ve got. I’ve got five, but none of us got the chain, did we so…

M1: Mine hasn’t even got pedals…

W2: No, mine hasn’t got pedals…

M1: Pedals nor chains so mine will never work!

W2: But if you’ve got pedals and no chain it’s not going to work anyway…

M1: It’ll have to be going downhill…

W2: And also that, um, that means the explanation for men making the bike work doesn’t because you, you…

M1: That’s right … of the two women and one man none of us drew…

W2: Have made the bike work.

M1: … yeah, and none of us drew a person … so the explanation about women wanting to put a person on there is hasn’t proven correct for you two….

W1: No, not with us … no.

M1: And mine is meant to be all about functionality and hasn’t … ah, I’ve got a little bird on my handlebars though….

W2: It’s very clear drawing though, yours…

W1: I think mine is more male than yours, maybe? Yes…

M1: I think you’re right…

Unit 11 METALS

Sophia: OK, so steel bodywork versus aluminium bodywork.

Peter: What about pre-use, then?

Sophia: Well, I think it takes a lot of energy to produce aluminium, compared with steel, because aluminium's made by electrolysis.

Peter: Yeah. So steel's better, presumably.

Sophia: I think so, yeah. But, hang on a minute with aluminium, it depends how much is derive from ore, and how much is recovered from recycled material. As far as I know recycling aluminium takes less energy. So I'm not really sure.

Peter: Presumably, it'll be mixed, won't it? For a given batch, there'll be so much new material and so much recycled material.

Sophia: Probably, yeah. OK, so that needs to be researched, then.

Peter: Is car bodywork galvanised when it's made from steel?

Sophia: Um ... good question. I'm not sure.

Peter: lf it is, if it has to be coated with zinc, the that would take extra material and extra energy So that's an important consideration.

Sophia: Mm, true. OK, so that's another question to note.

Peter: Then there's the energy consumed when they're transporting bulk metal to the car plant

Sophia: Presumably aluminium takes less energy to transport, being lighter.

Peter: I'd say so, yeah.

Sophia: OK. What about manufacturing?

Peter: Well, aluminium would be lighter to handle wouldn't it? lt probably takes less energy to cut, as well.

Sophia: Yeah. Not sure whether it takes less energy to weld, compared with steel.

Peter: Cood question. Another thing to check out

Sophia: Mm, what about in-use, then? | assume aluminium's better because it's lighter, so you consume less fuel.

Peter: Yeah. And it should last longer, as well.

Sophia: Mm, is that an environmental consideration, though?

Peter: Well, yeah, because if things last longer, they need to be manufactured less often.


Date: 2015-12-11; view: 232


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