Given below are some examples of wave motion. State in each case, if the wave motion is transverse, longitudinal or a combination of both, and also give reasons.
(a) Motion of a kink, in a long coil spring produced by displacing one end of he string sideways.
(b) Wave produced in a cylinder consisting a liquid, by moving its piston back and forth.
(c) Waves produced by a motor-boat, sailing in water.
(d) Ultrasonic waves in air, produced by a vibrating quartz crystal.