Pedal power provides
the force that pushes
me forward but, while
it looks like there is
nothing to stop me,
there is plenty of

fresh air in the way.

The air resists being

pushed out of the way.

Air resistance is also

called ‘drag’.

Drag

(Air Resistance)

(Pedal Power)

The air that we breathe is a gas that’s made

up of a number of different things – mainly

nitrogen, oxygen, argon and carbon dioxide.

When you breathe in, you are sucking in all of

those, along with a bit of water vapour and, if

you’re unlucky, a few pollutants as well. Air is a

kind of chemical soup that encircles the Earth.

We don’t normally see it or try to look at it, and

the air that we breathe, and walk through, is

something that we all take so much for granted

that most of the time we forget that it’s there.

Yet it is a substance that can be measured,

weighed and sealed in containers, just like

water – and if you now start to think of air a bit

like water, things will make a lot more sense.

The water in a pond is obviously a liquid, not a

gas, but liquids and gases behave in much the

same way. We can ‘bully’ liquids by shoving

them out of our way. If you were to walk into

a shallow pond, you could walk through it,

pushing the water out of your way. In a deeper

pond you might have to swim, using your arms

to push the water aside, so that you can take

its place and move forward. When you walk

out the other side of the pond, things get a lot

easier because you no longer have to push the

water aside. Yet you are still pushing air – that

chemical soup – out of your way. There are a

couple of basic scientific principles at work

here. The first is good old Sir Isaac Newton’s