Q: The pressure at the bottom of a lake, due to water, is 4.9 × 10^{6} N/m^{2}. What is the depth of the lake ?

Sol: Pressure P = h ρ g = 4.9 × 10^{6} N/m^{2}

density of water = 1000 kg/m^{3}; g = 9.8 m/s^{2}

Hence h = P/ρg = (4.9 × 10^{6})/(1000 × 9.8)

= 500m .