## mathematics in sport

While the athletes are flexing their muscles, why not train your brain with these two Olympic puzzles?

Will Britain be able to turn the home advantage into the top spot on the medal table this Games? Predicting medal counts is a tricky business, but, never afraid of a challenge, we will reveal our own predictions for the top 20 countries here on Plus on Friday. In the meantime, why not come up with your own mathematical method for predicting the results? To help you along, here are two articles we produced for the 2008 Games in Beijing:

Only four days to go until the start of the London 2012 Olympic Games! To get into the spirit, we cast our minds back to one of our favourite features of the 2008 Beijing Games: the beautiful aquatics venue, known as the water cube. Looking like it had been sliced from a giant bubble foam, the design was based on an unsolved maths problem. And although the bubbles look completely random, the underlying structure is highly regular and buildable.

Remember Frank Lampard's disallowed goal in the 2010 World Cup match against Germany? The ball hit the crossbar, landed well behind the line but then bounced out again. And it all happened too quickly for the ref to spot it was a goal. How these kind of (non)-goals happen and what can we do about them?

Horses, like all animals, have a number of different gaits. But how can they perform these complicated leg movements without having to stop and think? And why do they switch to a new gait when they want to go faster? Mathematics can shed some light on these questions.

A simple question to ask about kayak races is whether having lots of paddlers helps or slows the boat down? The kayak with two paddlers has twice as many "engines" to power it but it also has twice as much weight to drag through the water. Which is the dominant factor?

The men's and women's 100 metre freestyle swimming races are set to be two of the most glamorous events of the London 2012 Olympic Games. Much has been made of the swimming events for London 2012 because the previous 2008 Beijing Olympics saw an unprecedented number of new world records, due to the use of controversial swimsuits. So how do these suits improve performance?

If you look at the pattern of rowers in a racing four or eight rowing boat then you expect to find them positioned in a symmetrical fashion, alternately right-left, right-left as you go from one end of the boat to the other. However, the regularity of the rower's positions hides a significant asymmetry that affects the way the boat will move through the water.

Runners and cyclists can tolerate heat and cold but the thing they dislike most is wind. They know it produces slower times. Can we show them why?

What makes a perfect football? Anyone who plays or simply watches the game could quickly list the qualities. The ball must be round, retain its shape, be bouncy but not too lively and, most importantly, be capable of impressive speeds. We find out that this last point is all down to the ball's surface, the most prized research goal in ball design.