School of Physics

what is REALLY interesting is that there was a guy who did an experiment similar to what Joe did in the lectures - whether a solid can rolls faster than one with liquid inside. to test this he sealed ice in a bottle with a rod through it, and also liquid water in a bottle with a rod through it. he repeated the experiment several times and it was clear that the liquid water bottle rolled faster. HOWEVER, when he dropped the liquid water bottle, some of the water spurted out and some air was introduced inside the bottle. when he repeated the experiment afterwards, he found that the liquid water with air was actually slower than the bottle with ice...
http://www.youtube.com/watch?annotation ... feature=iv

he went into some explanation as well. (:

In the experiment in class, there was no air in either the high or low viscosity fluid. And the low viscosity fluid won.

In the experiment on Physclips,
http://www.animations.physics.unsw.edu. ... tm#rolling
there was air in with the water (proportionally more than in the Youtube expt). And water still beats the honey.

I never tried varying the amount of air (and don't intend to) but it might have an effect, because the flow is complicated with air present. (And not much like Taylor-Couette flow!)

Joe