# Thread: gravity on center of the earth

1. if earth was the only heavenly body in universe n we r in the center of the earth how much gravtiy we feel?????
plz answer this whosoever konws the nser

2.

3. We would feel no gravity at the centre of the Earth, whether the Earth was the only heavenly body in the universe or not.

4. At the center of the earth the earth's gravity is 0. However the gravity of the sun, moon, etc. would still be there.

5. Welcome, but please, no sms language.

6. Originally Posted by mathman
At the center of the earth the earth's gravity is 0. However the gravity of the sun, moon, etc. would still be there.
Very good point, well made. I totally missed that!

7. Yes, but the question was, how much gravity would we feel.

8. thank you but we calculate gravity by (Gm1*m2)/distancesquare and since the distance is zero will there be undefined gravity?????????????? its my logic if i m wrong correct me

9. Originally Posted by anurag
thank you but we calculate gravity by (Gm1*m2)/distancesquare and since the distance is zero will there be undefined gravity?????????????? its my logic if i m wrong correct me
The mass of the earth is not concentrated at a single point. When you are in the center of the earth, the attraction due to each particle of the earth's mass is offset by an equally massive particle, at an equal distance, pulling in the opposite direction.

A spherical mass can be treated as being concentrated at a single point in the center only as long as we are outside the sphere. The earth may be treated as being composed of concentric shells. Once we enter each concentric shell, that shell no longer contributes to the gravitational pull. At the center of the earth, we are inside all the concentric shells and the gravitational pull is zero.

10.

11. Originally Posted by Harold14370
Originally Posted by anurag
thank you but we calculate gravity by (Gm1*m2)/distancesquare and since the distance is zero will there be undefined gravity?????????????? its my logic if i m wrong correct me
The mass of the earth is not concentrated at a single point. When you are in the center of the earth, the attraction due to each particle of the earth's mass is offset by an equally massive particle, at an equal distance, pulling in the opposite direction.

A spherical mass can be treated as being concentrated at a single point in the center only as long as we are outside the sphere. The earth may be treated as being composed of concentric shells. Once we enter each concentric shell, that shell no longer contributes to the gravitational pull. At the center of the earth, we are inside all the concentric shells and the gravitational pull is zero.
That is correct. Here is another question, to promote critical thinking:

Our planet is not a perfect sphere. Is the gravitational force still zero at the center (ignoring the rest of the universe)?

12. Our planet is not a perfect sphere. Is the gravitational force still zero at the center (ignoring the rest of the universe)?
If you found a centre based on the shape, it will probably deviate slightly from the centre of mass of the earth, but I don't think it would be by much.

13. A uniform oblate spheroid would also have zero gravity in the center. As long as the shape of the earth is symmetrical, and the density is also symmetrical, then we can still argue that for every particle of mass on the earth which pulls on a body in the center, there is a mirror image particle directly opposite cancelling that particle's gravitational pull. If either assumption is invalid, then there could be some net gravity.

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