Philip Hammond, MP - Please Help With My Physics Homework
Picture the scene - you’re driving along the motorway at 70 mph when as you crest a hill, you suddenly notice a constellation of red brake lights ahead. There’s been some sort of incident, and the traffic has come to a complete stop.
You stand on the brakes and do everything you can to stop your car. Thankfully, you’d judged the distance to the car you were behind perfectly (21m) , and you manage to stop a few millimetres prior to an actual collision.
Now imagine the same scene, but instead of driving at 70 mph, you’re doing 80 mph, and you’re the same distance from the car ahead of you. How fast do you think you’ll be doing with the inevitable collision comes?
If you go to the Highway Code’s web site, Rule 126 has handy chart that’ll show you how overall stopping distance is related to speed:
The trouble is, this doesn’t go up to 80 mph - the government’s new economy-boosting proposed speed limit. So I’ve added this to the chart (click to enlarge):
What this shows is that the difference in total stopping distances between 70 mph (96 metres), and 80 mph (121 metres) is slightly greater than just the braking distance at 40 mph (24m).
In other words, at the point on the road at which you would have stopped from 70 mph, you’ll still be travelling at a shade over 40 mph.
So here’s a challenge to our marvellous Minister for [Motorised] Transport: I’ve only worked these numbers out using the laws of physics, and they might be wrong. So please can you test them out for yourself. Get in the car, drive at 80mph, and do be sure to let us all know if that 40mph impact knocks some sense into you.
In the meantime, here’s some TV to watch:
And some more here from our favourite impartial TV journalists: