Fixed 1 second of braking time won&#x27;t save you if the front car hits an immobile object.
The correct formula would be (1 + .046 mph) seconds [0], where mph is speed in miles per hour. It evaluates to 3.76s at 60mph and at 4.9s 85.
Note that 1 second of reaction time is not exactly generous: <a href="http:&#x2F;&#x2F;www.webpages.uidaho.edu&#x2F;niatt_labmanual&#x2F;chapters&#x2F;geometricdesign&#x2F;theoryandconcepts&#x2F;BrakeReactionTime.htm" rel="nofollow">http:&#x2F;&#x2F;www.webpages.uidaho.edu&#x2F;niatt_labmanual&#x2F;chapters&#x2F;geom...</a> - cites times &#x27;less than 2.5 seconds&#x27; to actual brake application.<p>[0] 1mph&#x2F;(9.8m&#x2F;s<i></i>2) in seconds, according to Google, assuming friction coefficient of 1