A sailboat race is held on a river that runs directly North to South, with a current of 12 knots. A 25 mile race is held going downriver (south). The first heat is held early in the day when there is no wind. The second heat, also going downriver, is held later, when there is a 12 knot tailwind (from the North). In which heat are the fastest times recorded?

(In reply to re(4): solution by Charlie)

I guess I'll give up. 

It still seems like magic but I finally found some references that suggest that you can have a positive feedback loop in the forces.  It just seemed like there was no way for the force of the water to push the baot into the air pushing the boat into the water pushing the boat even faster, that something would have to give in that feedback loop.

oh well.

-- Joel

Posted by Joel on 2007-02-15 22:27:30