Transverse and longitudinal waves can propagate in solids,whereas only longitudinal waves can propagate in air. Explain this statement.

(N/A) Mechanical waves require a medium for propagation because they depend on the elastic properties of the medium. There are two types: transverse and longitudinal.
In a transverse wave,the particles of the medium oscillate perpendicular to the direction of wave propagation,causing shear deformation. Thus,each element of the medium experiences shear stress.
Solids and strings possess a shear modulus (rigidity),meaning they can withstand shear stress. Fluids (liquids and gases) do not have a fixed shape and cannot withstand shear stress; therefore,transverse waves cannot propagate in fluids. However,both solids and fluids possess a bulk modulus,meaning they can withstand compressive stress. Since longitudinal waves involve compressive stress (pressure variations),they can propagate in both solids and fluids.
Thus,a steel rod (solid) possesses both shear and bulk moduli,allowing both transverse and longitudinal waves to propagate. Air (fluid) only possesses a bulk modulus,allowing only longitudinal waves to propagate. When both types of waves propagate in solids,their speeds differ because the shear modulus and bulk modulus have different values.