Question: Sea levels and Tides
The moon's tidal pull is due to the difference between its gravitational
force on the centre of the earth and that on its surface, and is about one
ten-millionth of the force of gravity on the earth's surface. The earth's
surface therefore ought to be displaced by about that fraction of the radius of
the earth, i.e. about 60 cm. The fact that the tides are much higher than this
is due to resonance effects and the shape of ocean basins and bays etc.
The reason there are no tides on land is simply because the land doesn't
"give" in the same way that a large body of water does, at least in time
available (a few hours). The tidal force is far too small to have any
perceptible effect on individual objects (leaves, flowers, even Jumbo Jets).
Tudor Hughes, Warlingham, Surrey.
|