What will be the height of the first floor if the pressure of water on the ground floor is $4\times {10}^4 \mathrm{Pa}$ and ${10}^4 \mathrm{Pa}$ on the first floor? (Density of water = 1000 ${\mathrm{kgm}}^{-3}$ and g = 10 ${\mathrm{ms}}^{-2}$)

The pressure of water on the ground floor (P₁) = 40000 Pa
The pressure of water on the first floor (P₂) = 10000 Pa
Density of water = 1000 ${\mathrm{kgm}}^{-3}$
By using the relation,
${\mathrm{P}}_1-{\mathrm{P}}_2=\mathrm{\rho gh}$
We get,

40000 - 10000 = 1000 x 10 x h 
$\frac{30000}{10000}=\mathrm{h}$
$\mathrm{h}=3 \mathrm{m}$
The height of the first floor will be 3m if the pressure of water on the ground floor is $4\times {10}^4 \mathrm{Pa}$ and ${10}^4 \mathrm{Pa}$on the first floor .