Explain which properties are necessary to understand the speed of mechanical waves.

(N/A) For the propagation of mechanical waves,the medium must possess two essential properties:
$1$. Elasticity: This property allows the particles of the medium to exert a restoring force when displaced from their mean position,enabling them to return to their original state.
$2$. Inertia: This property allows the particles of the medium to store kinetic energy and overshoot their mean position,which is necessary for the oscillation to continue.
By considering these two properties,the speed of a mechanical wave can be derived using dimensional analysis,where the wave speed $v$ depends on the elastic property (e.g.,tension $T$ or bulk modulus $B$) and the inertial property (e.g.,mass per unit length $\mu$ or density $\rho$).