Unit 8 gravity, friction and magnetism

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