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 answer 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.

Explanation

Now `P_0 = 0`
(a) (i) Force at bottom
`F_0 = rho gh A = 1000 xx 10 xx 0.2 xx 20 xx 10^-4`
`= 4 N (downward)`
(ii) Force at top `F_1 = 0`
Weight of water
`W = rho V g`
`1000 xx (1)/(2) xx 10^-3 xx 10 = 5 N (downward)`
Force by bottom on water `= 4 N (upward)`
Since water is in equilibrium,
Force by glass sides on water
=`5 - 1 = 1 N (upward)`
(b) Answer will not change because for solving problems, height, bottom area and volume are required, shape does not matter.