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Physics, Astronomy & Cosmology / Does a boat weigh less when the tide is out?
« on: 08/05/2008 11:34:18 »
Background:-
Gravitational or tidal drag is caused by the mutual gravitational attraction between the Earth and the moon. It is slowing the Earths rotation and driving the tides.
Tides are caused by a physical "bulge" or high-point following the Moon. When this "bulge" is located over the ocean the tides are out on land due to the sea's surface being "pulled" upward. When this gravitational "bulge" is over land the tide is in, i.e. the sea's surface is not being "pulled" upward.
Questions:-
Is the gravitational attraction sufficient to flex the surface of the Earths crust when the gravitational "bulge" is over land, or is the viscosity of the Earth too stodgy to be affected by the moons gravity? (Does the Earth get any "tidal heating" from internal friction caused by gravitational stretching/squeezing?)
If a boat is out at sea when the tide is out, does the boat and occupant(s) weigh less than when on land or when the tide is in?
Thanks
Gravitational or tidal drag is caused by the mutual gravitational attraction between the Earth and the moon. It is slowing the Earths rotation and driving the tides.
Tides are caused by a physical "bulge" or high-point following the Moon. When this "bulge" is located over the ocean the tides are out on land due to the sea's surface being "pulled" upward. When this gravitational "bulge" is over land the tide is in, i.e. the sea's surface is not being "pulled" upward.
Questions:-
Is the gravitational attraction sufficient to flex the surface of the Earths crust when the gravitational "bulge" is over land, or is the viscosity of the Earth too stodgy to be affected by the moons gravity? (Does the Earth get any "tidal heating" from internal friction caused by gravitational stretching/squeezing?)
If a boat is out at sea when the tide is out, does the boat and occupant(s) weigh less than when on land or when the tide is in?
Thanks