Basically my question has to do with two cars. Car 1's speed is determined in
a cell, say "C1" and can be anywhere from 1-100mph. Car 2's speed is in "D1"
and can also be from 1-100mph.

So I have three columns which are Time, and the positions for Car 1 and Car
2 in feet.

IE
Car1=50 Car2=70
0.0 | 0 | 0
0.1 | 7.3 | 10.2
0.2 | 14.6 | 20.4

etc.

So I want to figure out when car 2 would rear-end car 1. In this case it's
fairly easy, because 50mph is approx 73fps and 70mph is approx 102 fps, so
car 2 is gaining on car 1 by approx 30fps... etc. (Also in this case where
they depart simultaniously, car2 would never hit car1...)

The easy way to do this is to just graph the three columns and see where the
lines intersect.

HOWEVER, if I want to delay car 2 by X seconds, then I have to re-do the
graph by adding zeroes to the start of column C for the approprite amount of
time, right? Also, if I change the speed of car1 or car2 then I have to come
up with a whole new series of graphs.

I'm just trying to figure out if there is some formula I can generate that
would (a) automatically insert (or assume) leading zeroes and/or (b)
determine when car2 will rear-end car1 given an arbitrary speed of each.

Preferrably I'd like to just be able to have speeds for car1 and car2 in two
cells and have the output of the formula be "car2 will hit car1 after X
seconds." (Text not necessary, just "X.")

Thanks in advance for any thoughts y'all might have on this. At first I
thought it was going to be easy but it seems more complex than my original
idea. I figured I could use vlookup except that *what number am I looking
for?* I'm looking for the number where the lines cross... but I don't know
what that is except to look at the graph...

Again, thanks!