Question

Why transverse mechanical waves can not be propagated in liquids and gases?

Answer 1

To transmit a transverse mechanical wave the medium must be elastic so as to provide a restoring force when acted on by shearing stress. But liquids and gases can not sustain shear stress to provide restoring force, but rather start flowing when acted on by shearing stress.

Note: Transverse waves travel in the form of crests and troughs. They can be generated in media which have elasticity of shape or rigidity. Solid materials qualify for transverse waves as they posses this property.

Though water does not posses elasticity of shape or rigidity, it has another equally effective property, surface tension, by virtue of which its oppose vertical displacements of its particles, hence it also qualifies for transverse wave.