# ...Earth's Gravity...humm, does anybody keep the manual?

How come the Earth whith it’s magnetic fild pulls everything, and ordinary magnet-just metal (and not all of them)
How does it (the mag. fild) pull organic things like me and YOU on the surfice of our dear Earth. I heard something like: “bla. bla, bla, everything has it’s own gravity, bla bla bla, the bigger they are the more they curve space and time, bla, bla, bla, and so… what was I speaking about?!?”:smack: I WANT SHORT AND SIMPLE ANSWER THAT I COULD TELL MY SISTER. Please.

Gravity and magnetism are two distinct things.

It is the earth’s gravitational attraction, not its magnetic attraction, which causes you a problem if you step off a high building.

Your pocket magnet also exerts a gravitational attraction attraction - everthing does - but since it’s a bit smaller than the earth, its gravitaitional attraction is correspondingly smaller, and you don’t notice itl.

To repeat: gravity is not magnetism. It is a different force altogether.

Magnets only attract certain things. Gravity attracts everything.

Gravity is a function of mass. The Earth exerts a large gravitational pull because it is big and heavy. The Sun, which is bigger and more massive, has a correspondingly larger pull. You (because you also have mass) also exert a gravitational pull but it is really, really, really small and negligible next to the Earth’s pull.

The Earth does have magnetic fields, but this is not related to its gravitational pull.

Hope that helps.

To expand a little. Anything with mass is attracted to anything else with mass. So the earth is attracted to you just as much as you to it. The problem with gravity is that it is really really weak. So for you to have any noticable amount of attraction you need at least one of the things doing the attracting to be pretty big. Planet sized big. This doesn’t mean that everything else isn’t still attracted to one another, indeed that is how scientists worked out just how strong gravity is - by measuring the attraction that large lumps of metal had for one another. This was one of the more amazing and delicate experiments of classical physics. (I have seen the experiment done in a lecture theatre. Got a pretty rough answer, but one that was of the right general size. Very impressive it was too.)

Also, the further you move two things apart, the less attraction they have for one another. In fact it is worse than simple distance, every time you double the distance the attraction falls by four times. Which is why the sun might be many many times more massive than the Earth, but you body isn’t in a tug of war between the earth and the sun. However, since the Earth is still pretty big, and the sun immense, the mutual attraction they have, despite the huge distance apart, is enough to keep the Earth in orbit around the sun, instead of just wandering off into space.

As mentioned above, magnetism is simply a quite different force. It has nothing to do with gravity. Theoretical physicists have been trying for nearly the last hundred years to work out some way of relating them to one another. They probably were combined for about the first infentesimal moment of the life of the universe. But since then quite different. Gravity and magnetism simply don’t interact.

The Earth only has a fairly weak magnetic field, and that is due to rotating liquid metal inside it. Many planets have even weaker, right down to essentially no, magnetic fields. It is mostly luck the Earth has one. (Good luck as it turns out.)

You explain things well, Francis Vaughan.

The Earth is 98 million miles away from the Sun and gravity still keeps it in orbit. Not sure why we consider gravity so weak.

See that fridge magnet? In a contest between it and the earth when trying to move a paper clip, it wins.

Weak is subjective.

Compare Gravity to Magnetism:
If the Earth and the Sun were magnets…well, the sun would be 1 earth mass bigger.

Compared to, say, the electromagnetic, strong and weak nuclear forces, gravity is weak. The only reason it’s the dominant force in the universe is that the strong and weak forces only act at very short range, and most things are electrically neutral, which removes the influence of the electromagnetic force.

Well more importantly, similar electrical charges repel each other so you don’t get large concentrations of positive or negative charge. Mass on the other hand can accumulate into stars, planets etc.

To put it another way, it sounds crazy to call gravity weak if you trip and fall on your face. Like it’s said though, it’s not the fall that gets you, but the sudden stop at the end. Gravity is just what gets you started falling, but electromagnetism is what causes you to stop. The electrons of the ground repel the electrons in your body, causing a blunt force, and pain. The electric repulsion is what prevents you from falling through the Earth and into the center, where gravity is constantly trying to pull you and every other bit of matter in the vicinity.

That’s a good point, Yumblie. The gravitational force of the whole earth on your body can be overcome by the electromagnetic repulsion of a thin piece of wood.