Silly Question: A fear of bringing up the rear

RELATIVE speeds of the front and rear ends of cars are causing considerable controversy, after Geoffrey Walker last week asked why the latter go faster, writes William Hartston.

Dennis Hale took a frontist view: 'The front wheels, when turning a corner, follow a curved track of greater radius than that of the rear wheels, hence a greater distance. As the time taken is the same, the front wheels are rotating faster.' Ron Amsden agrees: 'The driven wheels travel further than the idle wheels, because of wheel slip,' from which he deduces that Geoffrey Walker's car must have rear-wheel drive.

Jean Amsden, meanwhile, writes to disagree with her husband. 'Put yourself in the place of the back of the car,' she says. 'You know that the front can see where it is going, can read the speedometer, clock, and road signs, so it knows exactly how fast it must go. But you can't see any of this, so you must go as fast as you can, in case you get left behind.'

Julia Hulm maintains, more simply, that the back is always trying to catch up with the front, so has to try harder, while Richard Gardiner writes from the RAC in Pall Mall to point out that since the back starts behind the front, it has to go faster if it is to have any chance of reaching the destination at the same time. 'This may not hold good for trains,' he adds. 'British Rail helpfully positions a notice, 'Front train starts here', at the back end of it.'

Peter Godfrey's question - Why do animals not have green fur? - was answered by Lindsay Leggett: 'It is so as not to confuse vegetarians.' D P Bull, however, thought it was because of the bad press accorded to sloths, which look green because of the algae in their fur. Mike Ferguson maintains that 'there are many animals with green fur. They are just so well camouflaged that we never see them,' as indeed Mr Godfrey had suspected.

This week, Julia Hulm asks why bones are idle (as in bone-idle) and if there is any way to invigorate them. R Dallyn wants to know why kamikaze pilots wear crash helmets. E J Rowe asks why the piece of cork floating in your wine stays on the drinking side when you turn the glass. And M Pratt asks why the new Post Office headquarters in Bristol has eight lines of address before getting to the postcode.