a manometer or vacuum gauge
Mercury is used in thermometers because it expands and contracts uniformly with temperature changes, providing accurate measurements. Additionally, mercury has a high boiling point, allowing for use in a wide temperature range. Colored water would not provide as precise measurements due to its variable expansion rates with temperature.
Mercury's density is around 13.54 x that of water, so the pressures (in mm of water) would be 13.54 x what they are for mercury - 100 mm Hg would be around 1354 mm H2O
Depends on the medium, and whether the ball is solid or not. A solid ball would float on mercury, sink in water. If it were hollow enough (or filled with, say, cork) it would float in water.
Mercury would not float on water. This is because the density of Mercury (5427kg/m3) is greater than the density of water (1000kg/m3).
Suppose so, but the mercury would fall, instead of rising with temperature increase.
Mercury is a dense liquid metal with a density of 13.6 g/cm^3 at room temperature, which is much higher than water's density. Therefore, mercury would sink in water.
Using water instead of mercury to measure atmospheric pressure will result in a less sensitive barometer due to water's lower density compared to mercury. As a result, the water column would need to be much taller to detect small pressure changes accurately. Additionally, water's tendency to evaporate can make the measurements less stable over time.
nope it would be impossible
yes, it is different because instead of reading the bottom of the meniscus, with mercury you would have to read the top from the direction the curve is
Not Much
No, however most moats were filled with spikes under the water so if anybody would try to cross it, they would fail.
You would find water ice inside some of the shaded parts of craters.