Friday, 25 February 2011

HIGH tide and LOW tide AGAIN?

Many students would still find it confusing to understand the phenomenon of high tide and low tide.  What causes it and why?

Simple reason is to associate it to gravity of the Earth and the Moon, and the pull of force is called gravitational force. Gravitational force exists between two objects with mass.  For smaller objects, this force is not very noticeable. However, for massive objects like the planets, this gravitational force creates a significant effect. Both the Earth and the moon exert a force towards each other. The gravitational force decreases with increasing distance, so the water nearest the moon is pulled more strongly towards the moon than the mass of the Earth itself.  This force causes the water of the earth to swell on the area directly opposite the moon –which is called HIGH TIDE.

But this effect is symmetrical, which means it is also high tide on the opposite side of the Earth.  (It is easier to imagine a rounded balloon, that when you press it in the middle, the two opposing sides are both going to bulge out, but in the case of the Earth and the moon, it is the pull of gravity that creates this bulge).  The earth and the moon are also revolving around a common center of mass, causing the oceans to be ‘flung outwards’. If there ever is a vast body of water on the moon’s surface, it would also experience high tide and low tide like the earth.

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