# Gravitational Field and free fall

ineedhelpwithhw
The acceleration of free fall at the equator is not equal to the acceleration of free fall at the poles.explain?

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exponent137
The main reason is centifugal force of spinning of earth. Besides, Earth is not a perfect spheroid, it is a little flattened because of this centrifugal force.

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Gold Member
The main reason is centifugal force of spinning of earth. Besides, Earth is not a perfect spheroid, it is a little flattened because of this centrifugal force.
i don't know what centrifugal force has to do with gravitation
gravitation is just a matter of distance and mass

Gold Member
centrifugal force just akes varitions in gravitation ... it can't produce it itself

Homework Helper
The original post did not ask directly about "gravity", it asked about "the acceleration of free fall". That has to do both with gravitational force and with "centrifugal force" (actually the fact that part of that gravity goes to supply centripetal force keeping the object from flying off the rotating earth).

exponent137
If you are on surface on equator, I think that this is clear. Centrifugal force pushes you up. But if you are above the surface of equator and you are falling toward earth, you are also moving in the direction of rotation, but this means, that you are falling slower in comparison to nonrotating Earth or on poles.

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centrifugal force just akes varitions in gravitation

faiziqb12
exponent137
But it is interesting if some meteoroid falls toward Earth on equator. It falls like toward non-rotation earth, thus it does not feel Earth's centrifugal force.

Maybe this is what annoying you.

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Gold Member
But it is interesting if some meteoroid falls toward Earth on equator. It falls like toward non-rotation earth, thus it does not feel Earth's centrifugal force.
maybe centrifugal force effects gravitation on land and not in the sky

exponent137
This is not precisely. If you throw a stone from equator, its acceleration is smaller because of centrifugal force. Because rotation of Earth is in-calculated in it.

Gold Member
This is not precisely. If you throw a stone from equator, its acceleration is smaller because of centrifugal force. Because rotation of Earth is in-calculated in it.
i said maybe

exponent137
Thus, centrifugal force causes also on stone in the air (which flies from earth), but not on stone which flies from the universe.

maybe centrifugal force effects gravitation on land and not in the sky
Centrifugal force exist only in the rotating reference frame of the Earth, no matter if on land or in the sky. In the inertial frame there is no centrifugal force, no matter if on land or in the sky.

https://en.wikipedia.org/wiki/Centrifugal_force

DrStupid
and as there is highest centrifugal force at the equator there the gravitational acceleration is decreased more as compared to the poles

How do you explain that the gravitational acceleration is increased at the poles (compared to non rotating body) even though there is no centrifugal force?

nasu
The acceleration of free fall at the equator is not equal to the acceleration of free fall at the poles.explain?
This looks a lot like an end of chapter question.
It should be in homework section, shouldn't?

Gold Member
How do you explain that the gravitational acceleration is increased at the poles (compared to non rotating body) even though there is no centrifugal force?
the gravitational force isn't affected at the poles by the centrifugal force{which is opposite in direction of gravitational force}...............
so at the poles the gravitation is somewhat the same as it should be...
but near the equator the centriful force plays its part so the gravitation gets decreased a little....

the gravitational force isn't affected at the poles by the centrifugal force{which is opposite in direction of gravitational force}.
It's only opposite in direction exactly at the equator, not on the rest of the Earth. At the poles it's zero, so it's not opposite to anything.

DrStupid
so at the poles the gravitation is somewhat the same as it should be...

It is not the same as it would be without rotation.

Gold Member
i just said somewhat

DrStupid
i just said somewhat

Then at the equator the gravitation is also "somewhat the same as it should be". At the poles the acceleration is 9.832 m/s² and at the equator 9.780 m/s². The centrifugal acceleration at the equator is 0.034 m/s² and therefore directly responsible for only 65% of the difference. That means there is an additional effect within the same order of magnitude.

Gold Member
Then at the equator the gravitation is also "somewhat the same as it should be"
somewhat always is used in contrast to another thing .................. for example here it was used in reference to gravity at equator........
and yes i must commit that the gravity at the poles is actually that very much equal in magnitude to unaffected gravitation that the changes are negligible..........
say me one thing is actually gravity is not 9.8 everywhere ...... then why we choosed it as a constant.............because changes are approx. negligible for us to take care of..........same is the case here

DrStupid
and yes i must commit that the gravity at the poles is actually that very much equal in magnitude to unaffected gravitation that the changes are negligible

That would be true if we wouldn't talk about the difference between the acceleration at the poles and at the equator. Compared to this difference the changes are not negligible.