## differential equation

*Plus*, we heard how a simple mathematical equation became the subject of a debate in the UK parliament.

**Chris Budd**and

**Chris Sangwin**continue the story of the mighty quadratic equation.

**André Léger**studies the fluid mechanics of food travelling through the intestines for consumer goods giant Unilever.

**Lewis Dartnell**solves these, and other, puzzles of animal patterning.

**mathematical modelling**.

**Herbert Huppert**tells us what happens when two fluids of different densities meet, for example when volcanos erupt and hot ash-laden air is poured out into the atmosphere.

**Matthew Keeling**describes some of the mathematical developments that have improved our understanding and predictive ability.

**Keith Moffatt**tells us about three of the posters from the series.

**John H. Webb**explains.

**Helen Mason**explains.

**David Henwood**discusses the vibrations that can be harnessed by musical instrument makers.