There's nothing like personal experience to add that edge of veracity to a textbook, but few authors can draw on an inspiration quite so outlandish as Peter Ogrodnik, whose Fundamental Engineering Mechanics (Pounds 14.99) has sold out its first edition inside six months.
Ogrodnik's passion is lawnmower racing - for years he took part in 12-hour, all night races with souped-up 60 mph lawnmowers against the likes of Oliver Reed and Stirling Moss.
In the book, Dr Ogrodnik uses methods of boosting lawnmower performance for racing as a case study for explaining, for instance, the theory of gears. The annual race at Wisborough Green, West Sussex, will take place as usual in June, but he will not be taking part.
"I love it but it just got too dangerous for me - I am too old for it," he says wistfully. "I get all the adrenalin rush I need by sailing these days."