|Thinking Distance (feet)||Braking Distance (feet)||Overall Stopping Distance||Ratio|
|(Speed in MPH)||(speed x ratio)||(TD + BD)|
These figures were arrived at through research carried out by the government in the 1930's. A car would be driven. A signal would be given and at that precise moment, a blob of paint was fired onto the road beneath the car. After a short interval, the driver would react, and start the process of stopping the car. As soon as the brake was pressed, another blob of paint was fired. Then finally, a third blob was fired at the point where the car finally stopped. Repeat at different speeds... It loosely fitted the pattern shown above, and was adopted as the accepted figures. Modern brakes, tyres and suspension, as well as such things as anti lock brakes mean that the braking distances are much shorter, but they've kept the original figures presumably so that it includes a safety margin. So when you hear the police say "It would have taken this vehicle the length of two football pitches to stop" they're using this formula. It's also velocity squared divided by 20 by the way.
Voyager two is travelling at around 34,000mph. This squared is 1,156,000,000. Divide that by 20 and you get 57,800,000. That's your braking distance in feet. Thinking distance, assuming the stopping would be carried out by a driver with normal capabilities would be a further 34,000 feet for a total overall stopping distance of 57,834,000 feet. That's 10,953 miles. I'm not sure what that is in football pitches.
This assumes a dry road, obviously. Braking distances can double in very wet conditions, and it can take up to ten times longer to stop when driving on ice.
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