Judging distances

Sir,

Considering two cars A and B being driven round a racing circuit separated by a constant 0.5 sec, at 180 mph they will be 132ft apart, at 90 mph 66ft apart, and at 45 mph 33ft, or only a couple of car-lengths, apart. This is simple arithmetic, and yet in these circumstances we hear commentators saying “B has outbraked A and closed right up on him, but A has superior acceleration and widens the gap again after the corner”.

While braking and acceleration are, of course, relevant in racing, bunching in slow corners is not necessarily the result of these factors, and commentators should be expected to be looking at time intervals and not misleading linear distances.

A commonplace illustration is the tailback at traffic lights. The car at the back has not necessarily caught the one at the front, neither does the latter have to rely on superior acceleration to get away first when the lights change.

Ken Fairton, Rye, East Sussex