Example $20\mathrm{.}1$: Determine the natural frequency of a machine foundation which has a base

area of $2\mathrm{.}20m2\mathrm{.}20m$ and a weight of $155$ kN including the weight of the machine. Take the

value of the coefficient of elastic uniform compression as $4\mathrm{.}4{10}^{4}k\frac{N}{m^3}.$