Tides occur in the oceans and seas due to which among the following? 1. Gravitational force of the Sun 2. Gravitational force of the Moon 3. Centrifugal force of the Earth Select the correct answer using the code given below.
Explanation
All three play a part. Tides are raised mainly by the Moon's gravitational pull and, to a lesser extent, by the Sun's: the Sun's tide-raising effect is a little under half the Moon's, because that effect falls off with the cube of distance and the Moon is far closer. The third force is the centrifugal force that arises as the Earth and the Moon revolve around their common centre of mass. On the side of the Earth facing the Moon, gravity is the stronger and draws the water into a bulge; on the far side, the centrifugal force exceeds the Moon's weaker pull and raises a second bulge, which is why most coasts get two high tides a day. When the Sun, Moon and Earth line up at new and full moon, their pulls combine into spring tides; at the quarter moons they partly cancel, giving neap tides.