To determine how long it will take you to stop assuming a constant rate of deceleration, you need only divide your starting velocity (in fps) by your rate of deceleration.
60 MPH = 88 fps. (fps=1.467 * MPH). If your deceleration rate is 20 fpsps, then stopping time = 88/20 = 4.4 seconds. Since there is a 1 second delay in hitting your brakes (recognition and reaction time), the total time to stop is 5.4 seconds.
To determine how far you will travel while braking you take 1/2 the starting velocity and multiply the result by the stopping time
.5 * 88 * 4.4 = 193.6 feet. Since we traveled 88 feet before we hit the brakes, we add that to 193.6 and end up with a total of 281.6 feet,
OR YOU CAN GO HERE ;D
http://www.onlineconversion.com/speed_common.htm
