math ?

[reality]

 we have a hill. It's 1 mile up and 1 mile down. constant grade.

My car is lacking power so can only average 15mph going up. How fast do I have to go down to average 30mph

 Hint; the answer is not 45 mph.

[Steve Wood]

Wertheimer was a tricky bastard

[reality]

Yep; but it proves you have to think way outside of the box some [all] times.

[Steve Wood]

for sure

[Shimy87]

assuming your not starting from a standstill going up and not stopping at the bottom.....my guess is 60mph

[Forzfed]

Constant grade tells me we are working with a triangle with 60' corners.  Your car weight is constant.  You minus gravity at a grade of 60' going up hill to obtain your final velocity and subtract it down hill to find the final velocity.  I just wokeup from night shift other wise I would attempt to solve it.

[Steve Wood]

You averaged 15 going up and you want to average 30 for the entire trip.

[jonasterg]

It's a tricky one because you need to realize speed is distance/time.  You want to double the speed and you're going to travel double the distance... so the total time can't change.  Strap on your rocket boots. 

[Steve Wood]

more likely to need a worm hole!

[daveismissing]

So I've used up all my time and now you want me to go twice as far. Government math?

[reality]

So I've used up all my time and now you want me to go twice as far. Government math?

Truckers are expected to do that every day,
And they wonder why there is a shortage.

[Shimy87]

so when do we get the answer/explanation

[Steve Wood]

I think Jonasterg and Dave have already figured it out.  It's Ron's thread so it is up to him but you have to do some calculating.  You have average velocities and you have distances so ...

[reality]

 https://fs.blog/2014/06/einstein-wertheimer-car-problem/

[reality]

I also like this statement

What was Max Wertheimer theory?
Image result for wertheimer and einstein
Max Wertheimer was one of the founding members of Gestalt psychology. According to his theory on Gestalt psychology, “There are wholes, the behavior of which is not determined by that of their individual elements, but where the part-processes are themselves determined by the intrinsic nature of the whole.