# Earth rotation speed if it was tidal locked to the Sun

• MKP81
In summary: For your first question, if a day took 365 days, the equator would move about 0.0036667 kilometers per day. For your second question, if the Earth were to be tidally locked with the sun, the distance between the Earth and the sun would have to be within 0.6 AU.
MKP81
Dear Forum,

I am filmmaker from Berlin and despite physics focus back in high school I am really bad at it. I am trying to get my head around some ideas I am working on and would kindly ask you for some tiny calculations. I hope this is OK and maybe even fun for someone here?

So my questions are:
The Earth spins at a speed of 465,1 m/s (A) at the equator, right?

How fast would the Earth spin at the equator if it would be tidal locked to the Sun (B)?

If the negative acceleration from A to B would take 20 years how many m/s slower the Earth would spin in a year?

Would the negative acceleration be linear or exponential if one passing object would "steal" the rotational energy through its own gravitational force. Like the moon does for example but much heavier of course.

What mass would such an object need to decelerate the Earth like this if it passes let's say about the distance of the moon?

I know it is nonsense. But fun to think about it!

I thank you so much.

welcome to the forum

hsdrop said:
welcome to the forum
Thank you hsdrop!

are you writing a store based off the questions you asked??
there is a separate forum for that on the site for writers and stories that they are writing about

Yes I do. It it better to post/move there?

hsdrop
in most creative writing storeys the writers forum is a bit more open to the "what if's" then the others just because the other deal in absolutes and lateral instead of the creative. throw i an looking up some of the answers to your questions now or at least the ones that i can explain some what easley

MKP81
MKP81 said:
The Earth spins at a speed of 465,1 m/s (A) at the equator, right?
yes the Earth does spin at that speed hears a graph that shows a little more of how fast the Earth spins according to where you live on the planet

MKP81 said:
How fast would the Earth spin at the equator if it would be tidal locked to the Sun (B)?
well if the Earth was tidal locked to the sun that would mean that only one side of the Earth would face the sun at all times so if you take the circumference of the Earth and divide it by a year you would get your spin speed that comes out to about 4.57477...km/h

as for the other questions that you asked i would need a little help with answering them completely right

MKP81
hsdrop
what exactly are you asking for? Are you asking how fast would the equator move if a day took 365 days or how close would the Earth have to be in order to tidally lock in the first place? That can't happen where it is, it's way too far from the sun.

hsdrop

## What is tidal locking?

Tidal locking is when a celestial body's rotational period matches its orbital period, causing one side of the body to always face its parent body.

## How does tidal locking occur?

Tidal locking occurs due to the gravitational forces between two bodies. As a smaller body orbits a larger one, the larger body's gravitational pull on the smaller body causes it to deform, creating bulges. These bulges then create tidal forces that slow down the smaller body's rotation until it becomes tidally locked.

## What would happen if the Earth was tidal locked to the Sun?

If the Earth was tidal locked to the Sun, one side of the Earth would always face the Sun, while the other side would be in permanent darkness. This would result in extreme temperature differences, with one side being extremely hot and the other extremely cold.

## What is the current rotation speed of the Earth?

The Earth's current rotation speed is approximately 1670 kilometers per hour at the equator.

## How would tidal locking affect life on Earth?

If the Earth was tidal locked to the Sun, it would greatly affect life on Earth. The extreme temperature differences would make it difficult for life to survive, and the lack of a day-night cycle would also have significant impacts on the environment and organisms' behavior and biological processes.

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