At 35 mph, which distance is the stopping distance?

• A. 320 feet
• B. 260 feet
• C. 180 feet
• D. 210 feet

Answer: (D)

Stopping distance combines two parts: the distance you travel while you notice danger and react (perception and reaction) plus the distance your car needs to slow to a stop once you brake (braking distance).

At 35 mph you’re moving about 51 feet per second. If you assume a typical reaction time of about two seconds, the perception/reaction distance is roughly 102 feet. The braking distance at that speed on dry pavement is usually around 100 feet. Add them together and you’re in the neighborhood of 210 feet.

So 210 feet matches the common, estimated stopping distance under normal conditions. If conditions are worse (wet roads, bald tires, slower reaction) the distance would be longer; if conditions are ideal, it could be a bit shorter, but 210 feet is the best fit for typical expectations.