JessicaRulestheUniverse.com

So there you are, driving to school or work or whatever when your phone buzzes. “I’ll just look at my phone for one second,” you think. “It will only be a second and I should be fine—right?” Wrong.

Let’s say you are traveling at some speed v and you take just one second to glance at your phone. That is one second that you are not looking at the road. What happens during that one second? First, let me define average velocity (in one dimension—I add that because I hate being technically wrong).

In this definition, ?x represents the change in position and ?t represents the time interval. Please stop saying velocity is distance over time—that is only sometimes true. In this case, I know the time interval is one second. If I solve this equation for the change in position, I get:

If the velocity is very small, the distance traveled in one second also is very small. OK, how about some values: Say you’re creeping along at just 1 m/s or 2.2 mph or 3.6 kilometers per hour. You travel 1 meter in one second. (No, I’m not going to convert that to feet. You just get in the habit of using metric units—the rest of the world long ago realized this is the best set of units.) But if you’re zipping along at, say, 25 m/s (56 mph, 90 kph) then you travel 25 meters in one second. That’s about one fourth of a football field or about two school buses. A lot can happen in that kind of distance.

Read it in Wired.