Why don't melting ice cubes make my drink overflow?

How does polio cause disease? Why does ice added to a drink not make the glass overflow when the ice melts? What's the point of the appendix? Is old poison, past its expiry date, still toxic? What techniques built the pyramids? How do we treat hypotension? Why do our brains use a disproportionate amount of energy for their weight? Could a fan push a boat along if the wind dropped? And is a dry eye after a cataract operation normal? Dr Chris and Clarence Ford have the answers... Like this podcast? Please help us by supporting the Naked Scientists