2) You pass a shop window at an optician in town and stop when you see that they in this window, to attract customers' e

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2 You Pass A Shop Window At An Optician In Town And Stop When You See That They In This Window To Attract Customers E 1 (78.83 KiB) Viewed 29 times

2) You pass a shop window at an optician in town and stop when you see that they in this window, to attract customers' eyes, has a large transparent U-tube filled with a reddish liquid, probably colored water. The tube is open at both ends, it is clearly visible, but still the liquid levels are at different heights. It's a communicating vessel in the highest grand, so how can this come about? The pipe appears to have a diameter of half a decimeter and you estimate the difference between the liquid levels to one centimeter. U From the bottom of the U-tube to the liquid levels it is about half a meter. When you look more closely at the liquid column whose level is higher up, you see a faint but clear layering in the liquid five centimeters down from the surface. It is a liquid that "floats" on top of the other! That explains it all. It's some kind of oil maybe? But what is its density?