[Guest]

You are in a motor-boat, in a river, sailing counterflow, and your engine is running with same power all the time. Then, your suitcase falls in to the water (your suitcase floats, it doesn't sink).

10 minutes after your suitcase fell, you realize that is missing, so you make a U turn in order to recover your suitcase.

¿How long will it take you to find it?

There is a real answer for this puzzle, I'll add it later.

P.D. English is not my native language, so, if something is unclear, feel free to ask.

Edited March 25, 2009 by sergiomn

[Guest]

10 minutes

[Guest]

It depends on how fast your engine is going and how fast the current is pushing downstream

[Guest]

10 mins.

[Guest]

it may sound absurd but i calculated the time taken to be ...

10 mins

:-)

EDIT: It doesnt take into count the time taken to stop the boat and reverse it and ofcourse the time taken to make the decision that you have to go back.

Edited March 25, 2009 by DeepS

[Guest]

The answer is 10 minutes.

Here is why:

Imagine you're inside a train, and left your briefcase while you're walking. Ten minutes after, you realize that you left your briefcase, and then you make a U turn in order to recover your briefcase. As you can tell it doesn't matter how fast the train is going, at any time, you'll find your briefcase in 10 minutes, as you are walking always with the same steps/minute (or speed should I say). That's why I mentioned that "the engine is running with the same power all the time".

The current speed is playing the same role as the train speed.

This is how Einstein used to explain part of his relativity theory, really cool I think.

Edited March 25, 2009 by sergiomn

[Guest]

well if i would have left my briefcase on the train, on return i would rather run

.. jokes apart this was a very tidy explanation..

and yes, Welcome to the Den!!

[Guest]

Assume x is speed of boat, y is speed of current. (And assume your U-turn takes no time)

Assume where you dropped the suitcase = 0

Location of boat after 10 min = 0 + (10x - 10y)

Location of suitcase after 10 min = 0 - 10y

10x - 10y - Ax - Ay = -10y - Ay

10x - Ax = 0

10x = Ax

A = 10

10 mins.

[Guest]

Very nice explanation to this sergiomn, I thought it was 10 min at first but couldn't explain why.....

Welcome to the Den!

[Yoruichi-san]

But what if instead of a boat...we had a seaplane...that was traveling at the same speed as the river...would it take off?

[Prof. Templeton]

But what if instead of a boat...we had a seaplane...that was traveling at the same speed as the river...would it take off?

Don't you start that again.

[Guest]

But what if instead of a boat...we had a seaplane...that was traveling at the same speed as the river...would it take off?

I think you wanna start another 50 pages arguing about wheather it takes off or not...