# Transcript

[text on screen] What do you know about friction?
CHRISTOPHER
It slows things down … it can come between almost any two surfaces – even air and water. The things don’t have to be solid.
I’ll do a demonstration.
This is the water. This is a stone skimming. You throw the stone, it skims the water and every time it skims the water it slows down because of the friction on the water and then eventually it slows down and sinks.
[text on screen] Are there any other kinds of friction?
CHRISTOPHER
Well, there’s air resistance, so when you’re dropping from a plane then air’s coming up and it slows you down. There’s only air resistance with certain like things down here. Watch … see, that’s a little bit of air resistance that slows it down, whereas if it was this pair of scissors it would just go neeoooww!