Where's the sweet spot?
A Gömböc is a strange thing. It looks like an egg with sharp edges, and when you put it down it starts wriggling and rolling around as if it were alive. Until quite recently, no-one knew whether Gömböcs even existed. Even now, Gábor Domokos, one of their discoverers, reckons that in some sense they barely exists at all. So what are Gömböcs and what makes them special?
Mathematicians explain how plants climb
What goes up must come down — or does it? Find out how to cheat gravity with Julian Havil.
The concept of a speed limit seems a simple one - until you think what can happen when a speed camera clocks a rotating wheel...
Have you ever noticed what happens when you spin a coin on a table? As the coin starts to fall over and roll on its edge, its spin gets faster and faster until it suddenly stops altogether.