If you imagine yourself at the center of the earth your are floating since the pull is the same around you. But let us say you could turn up the gravity as much as you want. Why aren’t you pulled apart? The net forces are zero, sure. But wouldn’t the body experience tension?

Question

If we compare it to a rope pulled by two equal forces in each end. The net forces would be zero and you would have static equilibrium, but the rope would still break if pulled hard enough.

Additionally, wouldn’t a metal ball uniformly surrounded by powerful magnets be pulled apart as well?

I am not sure why I can’t wrap my head around this, when it comes to the center of the earth.

In: 83

Answer 1

I don’t know if this is how it is usually done on this subreddit. But I just wanted to share what I have learned and I also believe I can explain it with the rope analogy.

Let us say we have a rope, pulled by 2N on each end.

Example 1;

2N <———————-> 2N This would give us Fnet = 2N-2N = 0 and a tension of 2N in the rope. Or a body, it would be pulled apart with enough force to overcome to tension.

BUT! Inside of the earth, or a hollow sphere. The forces that pull you, act everywhere at once so our rope would look like this instead;

Example 2;

2N-2N <———————-> 2N-2N This would give us Fnet = 2N-2N+2N-2N = 0 and a tension of 0N in the rope.

This is what I couldn’t wrap my head around at first. There is nothing pulling since everything cancels out. Since all the force are uniform and acting everywhere and not just two opposite forces on each end. I hope this helps others that were confused about this as I was.

Edits; Spelling and trying to make it looks cleaner.