I gave the next problem to my students the other day to show them that, if we learn to see our problems in a different new point of view, we may be solving them on a much simpler way.
A lumberjack lives on the side of a river and takes his canoe to go work (somewhere upstream).
On a certain day, when heading to work, he passed through a floating log on the river, exactly one mile away from his house. He proceeded his journey until, after an half of hour he realized he forgot his saw. He immediately turned the canoe around to go pick the saw he left home.
Amazingly, he arrived his house exactly at the same time has the log he saw on the journey up.
Assuming the lumberjack paddled at the same rate in his entire journey, what is the velocity of the stream of the river?
It's possible to solve this on a very simple way. I didn't give any clues to my students, but I will give one to you:
If you read the problem with Einstein eyes, you will solve it in ten earthling seconds.
I'm trying to evaluate the complexity of the problem. Are you capable to solve it in a blink of an eye?