#### Cogs and Gears

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

#### Here are some of the cogs we can to think about:

These are some different sized cogs that can click in together.

They rotate around the middle (where the number is). They can be joined in a variety of different ways. For example, we can think about the peach coloured 10 joined with the purple 15. If the 15 is turned around exactly once in a clockwise direction what will happen to the 10?

Then what if the 15 was joined to the orange 5 instead, if the 15 now turned round exactly once in a clockwise direction what will happen to the 5 cog?

Now you can explore other cogs joined together and say what happens when one of them is turned.

To explore further, these cogs and more can be downloaded here allcogs.doc

You are probably curious about what happens with joining cogs of different sizes and asking yourself some questions. Here are some starting ideas that you may lead you to be curious about what happens.

**Three cogs together.**
Try joining 3 cogs together what happens to the other two when you rotate one just once. You choose which 3 cogs you want to use.

In this picture, the black blob is the handle and I turn it around once clockwise.

The question then is what has happened to the 4 and 6 cogs, how much have they turned and in which direction?

**Two cogs together**
Join 2 together how many times will you have to turn the bigger one round for the smaller one to rotate exactly 4 or 5 times. In this picture, the black blob is the handle and as I turn it anticlockwise I keep note of both the 4 cog (to see when it has turned exactly 4 or 5 times) and the 12 cog to see how much it turns.

More Cogs

Try fitting 4 cogs together, and what happens when you rotate one of them once.

Try fitting 6 cogs together, and what happens when you rotate one of them once.

In this picture, I turn the 9 just once clockwise and try to see exactly what happens to the other three cogs

#### Or you might be curious about . . .