In wihch direction does log floating down the river spin?

Question

The log floats perpendicual to the flow, and moves
freely under water drag and gravity pull?

#### <-counter-cw
######## ########ooo clockwise->
######## #######ooooo# ##########
######## ########ooo## ############ #########

Answer 1

It depends on the movement of current underwater.

Answer 2

Depends on whether the log is north or south of the equator.

http://en.wikipedia.org/wiki/Coriolis_effect



Quoted from source:



"ROTATION OF EARTH …

The spinning of the Earth has an effect on moving objects: it causes them to deflect slightly to the right in the Northern Hemisphere, or to the left in the Southern hemisphere. The "Coriolis effect" applies equally well to a river or a ballistic missile. But don't be fooled; its because of this deflection to the right that bath water goes down the drain in a counter-clockwise rotation (North of the Equator)."



So I would conclude that the eddy currents would spin the log counter-clockwise in the northern hemisphere. (along it's vertical axis - not it's longitudinal axis.)



Good question!

Answer 3

Air drag pulls the log counterclockwise. I don't see any other net torques about its center. Of course this assumes nice, smooth, flow, which you'll never see.