# What happens with the sea level due to the centrifugal acceleration?

In summary: Earth's bulging equator.The kind of equilibrium state that is used in the process of manufacturing a parabolic dish is the same as the equilibrium state of the bulging Earth.
What happens with the sea level due to the centrifugal acceleration?

This sounds like a homework question. What do you think happens?

Thanks for the help. I was just doubtful how it will vary in the rotating frame of reference. I know about the change in effective gravity. I could put them in formulae from books and derive the expression. But I wasn't just sure about the physics behind it.

Is the effective gravity at equator less because the centrifugal force acts in a direction opposite to it? How does that effect sea level? That is what I want to know.

granpa said:

I think I got it. A sphere of freely flowing material in free-fall, such as a planet in formation, forms a shape reflecting the balance between internal gravity and centrifugal force from its rotation. (Reference: http://en.wikipedia.org/wiki/Centrifugal_force_(rotating_reference_frame)). So since the effective gravity is low at poles, the sea level is high and vice versa at equator. Am I right?

I think I got it. A sphere of freely flowing material in free-fall, such as a planet in formation, forms a shape reflecting the balance between internal gravity and centrifugal force from its rotation.
Since the gravitational force is much greater than centrifugal force even at the equator, this is not the case.

So since the effective gravity is low at poles, the sea level is high and vice versa at equator. Am I right?
That is exactly backwards. Gravitation is greatest at the poles because (a) the poles are closer to the center of the Earth than is a point on the surface of the Earth at the equator and (b) there is no centrifugal force at the poles.

Thank you DH. That was good explanation.

One way to look at sea level is that it is a constant potential energy surface, where the potential is that due to gravitation plus that due to centrifugal force.

D H said:
One way to look at sea level is that it is a constant potential energy surface, where the potential is that due to gravitation plus that due to centrifugal force.

Does that mean the potential energy is constant everywhere on the surface of the sea? or does that mean the Earth's surface is in hydrostatic equilibrium?

Does that mean the potential energy is constant everywhere on the surface of the sea? or does that mean the Earth's surface is in hydrostatic equilibrium?

Whether potential energy is constant everywhere depends on how you choose between two options for defining potential energy for this case.

You can opt to define as follows (this is the usual choice): there is a constant potential energy if there is no tendency to drift away in a particular direction. Here on Earth there is no tendency to drift northward or drift southward. It follows that the effective potential is the same everywhere on Earth.

The other option is to compute the Newtonian gravity from first principles (which means you need to compute the Newtonian gravity exerted by the reference ellipsoid). That gravitational potential is highest at the equator, and lowest at the poles.

At MIT, in the Atmosphere, Ocean and Climate Dynamics, students can http://www-paoc.mit.edu/labweb/lab4/gfd_iv.htm" . The kind of equilibrium state that is used in the process of manufacturing a parabolic dish is the same as the equilibrium state of the bulging Earth.

Another example is the parabolic shape of a mercury mirror for astronomic observations. Example: the http://www.astro.ubc.ca/LMT/lzt/index.html"

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## 1. What is centrifugal acceleration and how does it affect the sea level?

Centrifugal acceleration is the force that occurs when an object moves in a circular motion. In the case of the Earth, its rotation creates centrifugal acceleration that is strongest at the equator and gradually decreases towards the poles. This acceleration affects the distribution of water in the oceans, causing the sea level to be slightly higher at the equator and lower at the poles.

## 2. Does the centrifugal acceleration cause the sea level to rise or fall?

The centrifugal acceleration does not directly cause the sea level to rise or fall. However, it does contribute to the overall shape of the Earth and its rotation, which can indirectly affect the sea level through other factors such as ocean currents and tides.

## 3. How much does the centrifugal acceleration affect the sea level?

The centrifugal acceleration has a very small effect on the sea level, with a maximum difference of about 21 centimeters between the equator and the poles. This is a relatively small contribution compared to other factors such as melting ice sheets and thermal expansion of water due to climate change.

## 4. Is the centrifugal acceleration constant or does it change over time?

The centrifugal acceleration is not constant and can vary over time due to changes in the Earth's rotation and the distribution of mass on its surface. These changes are very small and are constantly being monitored and measured by scientists to better understand their impact on the Earth's systems.

## 5. Can the centrifugal acceleration be manipulated to control the sea level?

No, the centrifugal acceleration is a natural force that cannot be manipulated or controlled by humans. While it does have a small impact on the sea level, it is not a significant enough factor to be manipulated for the purpose of controlling the sea level. Instead, we must focus on addressing the larger factors that contribute to sea level rise, such as climate change and human activities.

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