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# Physics/gravity questions

Question
QUESTION: Hi,

Is the gravity inside space station is absolute zero or little gravity is felt? Why the gravity is low in space station, moon compared to earth, is it because their mass is very less? If there had not been sun, will gravity be still there in earth?

Regards

ANSWER: There is little gravity felt.  Obviously there's enormous gravity to keep the giant space station slinging around in orbit at over 7 kilometers per second.  The mass is constant, but because it is in a state of constant circular motion with gravity, everything moves exactly the same way and no gravity is felt relative to the other objects.  On Earth, gravity pushes you against the ground.  Up in space, the floor moves with you, so gravity doesn't press you against it.

---------- FOLLOW-UP ----------

I wanted to know why there is less gravity in space station. If gravitational waves travel from Sun to earth (as I read in one article), why the same gravitational waves does not impact the space station.

Also if there had not been sun, will there be gravity in earth?

ANSWER: What article?  Gravitation does not work that way.  All objects with mass have a gravitational field.  The Earth has its own gravitational field, just like the Sun.  There's not much less gravity on the space station than on Earth, you just don't feel it because you're in orbit.  The gravity just keeps you and the space station moving in orbit together and not flying off into space.  Because you move together with the space station, you don't feel a gravitational pull towards it.  You float, with that feeling like you're falling.  The gravitational pull is still there or you'd fly off into space.  It's hard for most people to truly understand, but think about the gravitation in combination with the circular motion.

---------- FOLLOW-UP ----------

>> What article?  Gravitation does not work that way.

from time 7:46 where they state that if sun does not exists, the gravitational disturbance would reach earth after sometime and gravity in earth will be affected. Is my understanding correct?

Thanks

No, gravity in the Earth will not be affected.  The gravitation making the Earth and everything in it orbit the Sun would be affected.  So yes, you misinterpreted the thought scenario of the Sun magically disappearing, it is not the source of Earth's gravitation.

Physics

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