# Is Michelson Describing Earth Tides or Ocean Tides?

• cragar
In summary, George Gamow explains in his book on gravity that the American physicist AA Michelson discovered that the Earth's surface is deformed by one foot every 12 hours due to tidal forces from the Moon and the Sun. This is due to the Earth's elasticity, which allows it to deform under small stresses, but behave more like a plastic when stressed beyond a certain limit.
cragar
I am reading George Gamow's book on gravity and in his book he says:
The American physicists AA Michelson found from his experiments that every 12 hours
the the surface of the Earth is deformed by one foot, as compared with a 4-5 foot
deformation of the ocean's surface.

This seems weird to me, does this have to do with the centripetal force because we are rotating. Or is he's just talking about the ocean tides,

cragar said:
This seems weird to me, does this have to do with the centripetal force because we are rotating. Or is he's just talking about the ocean tides,
He's talking about Earth tides (wiki article: http://en.wikipedia.org/wiki/Earth_tide). Just as the oceans are subject to tidal forces, so is the Earth as a whole. Those tidal strains on the Earth would have no effect if the Earth was a perfect rigid body. It isn't. The Earth is better described by the theory of elastoplasticity. It deforms elastically to small stresses, but above some limit it starts to behave more like a plastic.

## 1. What causes ocean tides?

The gravitational pull of the moon and the sun on the Earth's oceans is what causes ocean tides. The moon's gravitational pull is stronger because it is closer to the Earth, which is why it has a greater effect on tides than the sun.

## 2. How do tides affect the Earth's surface?

Tides play a crucial role in shaping the Earth's surface by constantly moving large amounts of water and sediment. They contribute to erosion, sediment transport, and the formation of land features such as beaches, tidal flats, and deltas.

## 3. Why does the timing of high and low tides change every day?

The timing of high and low tides changes every day due to the moon's orbit around the Earth. As the moon orbits, the Earth rotates, causing a change in the location of the moon relative to a specific point on the Earth's surface. This change in position affects the strength of the moon's gravitational pull, resulting in changes in the tides.

## 4. How do ocean tides impact marine life?

The constant ebb and flow of tides provide essential nutrients to marine life, which rely on the tides to bring in food and remove waste. Tides also create diverse habitats for marine creatures, such as tide pools and intertidal zones, where a variety of species can thrive.

## 5. Can tides be predicted?

Yes, tides can be predicted with a high level of accuracy using mathematical models and tide tables. These predictions take into account factors such as the moon's phase, the sun's position, and the Earth's rotation, among others. However, unpredictable events such as storms and strong winds can affect the actual height and timing of tides.

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