3. Figure 3(a) shows a horizontal tube containing air trapped by a mercury thread of length 5 cm. The length of the enclosed air column is 7.5cm. The atmospheric pressure is 76 cm Hg.
7.5cm cm
Figure 3(a)
5 m
Figure 3) by
The tube is then turned vertically with its mouth facing down as shown in Figure 3(b).
a. Determine the length 1 of the air column. (3 marks)
b. State the reason why the mercury thread did not fall out in Figure 3(b). (1 mark)
