How to figure out a passing cars speed?

Question

How do you figure out the speed of a car in another lane when you are going 80 and the other car is clearly going faster than you? Isn't there a scientific method of counting time and multiplying it by something? I hope i get an answer because this has been bugging me for a long while

Answer 1

well...little bit of physics... speed = distance over time

In order to figure out how fast they were going, you would need to be able to calculate how long it took them to go from beside your car to a point ahead.  Without getting out of your car and getting a precise measurement, all you can really do is guess...Do it the fun way and follow them...haha!