Question

What type of mechanical waves do you expect to exist in (a) vacuum (b) air (c) inside the water (d) rock (e) on the surface of water? 

Answer 1

 (a) No wave possible as there is no particle. 

(b) Longitudinal waves (direction of motion of particles parallel to direction of propagation of wave)

(c) Longitudinal 

(d) Both are possible 

(e) Combined longitudinal & transverse (ripples)