Suppose the glass of the previous problem is covered by a jar and the air inside the jar is completely pumped out. (a) What will be the answers to the problem? (b) Show that the answers do not change if a glass of different shape is used provided the height, the bottom area and the volume are unchanged.
When the glass is covered by a jar and the air is pumped out of the jar, atmospheric pressure has no effect on the glass.
(a) Force exerted on the bottom:
(hρwg) × A
=(20 × 10-2 × 103 × 10)20 × 10-4
(b) mg = h × ρw × g × A + Fs
⇒ Fs = 5 - 4 =1N
c) If we use a glass of different shape with same volume, height and area, then there will not be any change in the answer.