Question

If you invert a tube of mercury 1.5 m long in a dish of mercury, how long would the vacuum space be above the mercury in the tube?

A) 0.5 m
B) 1.5 m
C) 3.0 m
D) 0.0 m

Answer 1

The vacuum space above the mercury in an inverted tube that is 1.5 m long would be 0.74 m, considering that atmospheric pressure supports a 760 mm column of mercury at sea level.

Step-by-step explanation:

The length of the vacuum space above the mercury in an inverted tube when setting up a simple barometer can be calculated by knowing the standard atmospheric pressure and the density of mercury. Standard atmospheric pressure at sea level is able to support a column of mercury approximately 760 mm high. If you have a tube 1.5 m long (1500 mm) and the atmospheric pressure can only support 760 mm of mercury, then the vacuum space will be the difference between the length of the tube and the height of the mercury column. Therefore, the vacuum space will be 1500 mm - 760 mm which equals 740 mm, or 0.74 m. So, the length of the vacuum space would be 0.74 m, which isn't an option provided in the question suggesting there might be a mistake either in the question options or in the understanding of the problem as the value should have been 0.75 m to match one of the given options.