Thread: Strongest point of gravity

Why is it, that an object's gravity is strongest at the surface?

I would think it would be at the core, or middle-most area.

Any explaination or easy-to-understand math for this, or is this one of those
"thats just the way it is"

in the center there is no net gravitational force because all of the gravity from the mass cancels each other out.

On the surface all of the mass is pulling in the same direction.

Now the center actually is the deepest point of the gravitational well. However has no gravitational force.

Originally Posted by Joe McCarron

Why is it, that an object's gravity is strongest at the surface?

I would think it would be at the core, or middle-most area.

Any explaination or easy-to-understand math for this, or is this one of those
"thats just the way it is"

gravity depend on the mass of the object no in the core.gravity depend too in the radium of a planet or object. gravity don't cancels out in the surface of an object. gravity is always the same depending in the mass of the object

Originally Posted by Mario Garcia

gravity depend on the mass of the object no in the core.gravity depend too in the radium of a planet or object. gravity don't cancels out in the surface of an object. gravity is always the same depending in the mass of the object

This is true of point masses. However, it is not true of extended bodies like planets and footballs. This is because extended bodies are composed of subatomic particles, which may be considered as point masses.

Look at it this way:

• If you stand to the right of a pair of objects, then their combined gravitational force pulls you to the left.
• If you stand to the left of a pair of objects, then their combined gravitational force pulls you to the right.
• If you stand between two objects, then they each pull you in opposite directions. There is a point between any two objects where their gravitational fields exactly cancel.

Just as in the case of pair of objects, there is a point on the interior of a solid object where gravitational force cancels out. In the case of a perfectly spherical hollow shell, the gravitational force cancels out everywhere within the void.

Originally Posted by tom

in the center there is no net gravitational force because all of the gravity from the mass cancels each other out.

Wow, i cant believe that didnt make sense at one point. It seems like a pretty straightforward concept.
It's not so much lack of gravity, as much as it is, gravity pushing at the center from every direction.

If i got on an elevator to the center of the earth, would i feel gravity, slowly fade as progressed to the center?
Or would it be more like a sweet spot in the middle, where the borders of "zero-g" are more defined?

Actually there is an interesting example that if you drilled a hole between any two points on the earth ( or any sphere-like object ) and ignored air resistance that dropping an object would take the exact amount of time to get the other side of the hole regardless of the length or angle of the hole.

For the earth it is 84.5 minutes.
Hole Through the Earth Example

Now ... one point with all of this is that the center of the earth is the point with the greatest potential gravity ... so like when a star collapses it will collapse from the core.

Originally Posted by Joe McCarron

Wow, i cant believe that didnt make sense at one point. It seems like a pretty straightforward concept.
It's not so much lack of gravity, as much as it is, gravity pushing at the center from every direction.

If i got on an elevator to the center of the earth, would i feel gravity, slowly fade as progressed to the center?
Or would it be more like a sweet spot in the middle, where the borders of "zero-g" are more defined?

yep gravity cancel out like this when a object is between two bodies that have the same mass but when we talk about one object is different
you right.

When you are the center of a spherical object the forces from all the mass symmetrically distributer around you would all cancel... equally tugging you all all directions with a net total tug on you of Zero. Cool 'eh?

Assuming a body of equal density, the point where gravity is strongest is indeed on the surface. However, if the object gradually becomes more dense the further you travel inward, gravity may either increase or decrease, depending on how the density varies between the surface and the centroid.