Centripetal acceleration question?

Correct.

Yes. You do not need energy to "retain the motion of orbit." Indeed, you would need a truly massive amount of energy to reduce that amount of momentum.

 

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Ok thank you , good enough to convince me at this time.

 

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I was just double checking things sorry it is my nature, your version accepted now and accepting that light is not strong enough in force.

 

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Maybe you should request the closure of this thread as well then?

 

I have had my answers so yes this can be closed all though this thread has value in showing anyone with the same idea about light force having the strength to oppose gravity , that the idea is not warranted.

 

The force acted by the sunlight on earth can be calculated. Look for example here: http://en.wikipedia.org/wiki/Radiation_pressure
You see that the sunlight gives a pressure \(P=9.08 \mu Pa \). So by knowing earth radius \(R_e \), you can calculate the force acting on the earth. I won't show it but by summing all the force at the different angles, it can be shown that the total force will be \(F=\pi P R_e^2 \). The acceleration that is added to the earth due to the light pressure will be (using Newton's second law) \( a = \frac{\pi P R_e^2}{M_e}\). Using the values we get that the acceleration is about \(7\times 10^{-19} \frac{m}{sec^2}\).
In order to understand how small is this acceleration, a body having this acceleration changes its velocity by \(1 \frac{m}{sec}\) in about 44 billion years. Do you think that this force is negligible?

 

Holy spit, I knew the amount was insignificant but good grief... I didn't realize it was THAT much so XD

I reckon we'd be better off trying to get everyone on one side of the planet to break wind at the same time!

 

Not sure if anyone has reviewed this....
"The earth only ever having one side in the light" is not applicable to Earth.
Our Moon only ever has one side facing earth, and in a few billion years hence, the Earth will also only ever have one side facing the Moon. This is called a captured geosynchronous orbit from memory and is caused by tidal gravitational effects.
When this happens of course, a day on earth will be equal to a lunar month.
Will the earth only ever have one side facing the Sun and be tidally locked?
If this is at all applicable, and I would say yes, it would probably be in a huge time frame, that would outlast the life of the earth anyway and a bloating Sun.