A glass full of water has a bottom of area $20c{m}^2,$ top of area $20c{m}^2,$ height 20 cm and volume half a litre. (atmospheric pressure $=1.0\times {10}^{5}N/m^2$ . Density of water = 1000 $kg/m^3$  and $g=10m/s^2$ ).

The pressure intensity at the bottom of the container is 
$P=h\rho g=0.20\times 1000\times 10=2\times {10}^{3}N/m^3$ 
Force at the bottom of container 
$=P\times$  base area  $+P_a\times basearea$
$=2\times {10}^3\times (20\times {10}^{-4})+(1.\times {10}^5\times 20\times {10}^{-4})$  
 $=204 N$ 
b) Weight of the water in the container 
 $=$  Volume $\times$  density of water  $\times$ g
 $=0.5\times {10}^{-3}\times 1000\times 10=5N$ 
From the diagram, the force exerted by the container is in upward direction (because $(P_2>P_1)$ . Let force exerted by sides of container is F, then 
$\therefore 4+F=5N$ 
$\Rightarrow F=1N$ 
 
From the diagram, the force exerted by the container in upward direction (because  $(P_2>P_1)$. Let force exerted by sides of container is F, then 
$\therefore 4+F=5N$ 
 $\Rightarrow F=1N$