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# How many feet does a car going 70 mph travel after braking before it comes to a stop?

Wiki User

2012-09-06 22:56:15

252 feet or less on typical dry road in US.

The basic answer is based on US Department of Transportation minimum requirements, which requires that brakes, tires, suspension, result in a passenger car being slowed at a rate of 21 feet per second per second (21fps^2) or better. If we convert 70mph to feet per second (multiply 70 x 1.467) we get 103 feet per second. So the time it takes to stop will be 103/21, or 4.9 seconds. Using straight line deceleration this comes to 252 feet.

If everything is in good shape and typical dry road, it will take the brakes 252 feet to stop after brakes are applied. This doesn't include reaction time yet (0.4 seconds for an alert driver), as the car will travel 41 feet before he even hits the brakes. We add this to get total of 293 feet, if you include reaction time. Note that all US cars well exceed these limits, providing for a safety factor for wet roads, and other factors. You should find under ideal conditions the actual braking distance will be under 170 feet.

Wiki User

2012-09-06 22:56:15
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