Marcus du Sautoy presents a problem about the average speed on his imagined commute.

Olympics Physics: Calculating Average Speed in the 200m Breaststroke Our resident physicist breaks down a swimmer's speed in the men's 200-meter breaststroke.

SPECS average speed cameras can calculate average speed over distances between 75 metres and 20 kilometres (12.4 miles). They appear in sequence on motorways at least 200 metres apart.