(i) Wave refers to the energy that flows through the water, making the water particles travel in circular, rising and falling motion. The energy is a result of the wind blowing over the water surface. Waves break at the shorelines and lose the energy to the landmass.

(ii) Waves in the ocean get their energy from the wind. When wind blows over water, it leads to the formation of ripples. On the surfaces of open seas, this forms waves. The wind propels the waves forward, while the gravity pulls the crest downward.

(iii) It refers to the periodic rise and fall of water twice a day, which occurs due to the gravitational effects of sun and moon on the free surface of earth’s water bodies.

(iv) Tides are caused by the gravitational pull exerted by the moon, and also by the sun. the free surface of water responds to the pulling effect of moon’s weight periodically rise twice a day. Another cause for tides is the centrifugal force of earth’s rotation, and tides are the result of the difference between these two forces.

(v) Tides help in navigation, as high tides raise the level of water. This helps the large ships to enter the harbour, as they would not be able to enter in at the shallow hours.