When you drop a ball from above, why doesn't it drill through earth?

[tarekatpf]

First of all, I want to say that I am totally ignorant about physics. And I do not understand the general concepts of physics at all.

Now coming to the question.

Suppose, you drop a green tennis ball from above.

Now It usually lands on Earth and stop there ( ignore the bounces for now. ) Suppose, the point at which the green ball lands is a red ball. Since the Earth is made of ''a mass of balls'' ( to get the concept, I am using such metaphors ), below the red ball should be another ball, and below that another ball, and so on, till you reach the opposite point on the earth, which is, suppose, a pink ball.

Now since all the balls from the red ball upto the pink ball is drawing the green ball toward them, how can this one little green ball stop just over the red ball ignoring the pull of all the balls between the red and the pink one?

Shouldn't it just ''break the red ball'' and keep reaching toward the next ball and break that too? I mean, drilling through earth?

I know the Earth is more or less a sphere. So are the pulls from balls around the red ball preventing the green ball from drilling through earth?

 

[siddharth23]

I have a strong urge to ask you if you are high on pot :P

Anyways, what exactly mean by 'pulls from the balls' and 'break the balls'?

 

[Drakkith]

There's a couple of factors at work here, but I think the main one is that objects cannot pass through other objects because there is a repulsive force between them when they touch. They cannot break through objects unless they can break the bonds holding the objects atoms and molecules together. The force of gravity simply cannot accelerate a tennis ball to a high enough velocity for it to break through another tennis ball.

Does that make sense? It is very difficult to explain if you know nothing about physics. An understanding of at least the very very basic fundamentals is required if you truly want to know why.

 

[Drakkith]

I have a strong urge to ask you if you are high on pot :P

Anyways, what exactly mean by 'pulls from the balls' and 'break the balls'?

I assume he's asking why gravity does not cause objects to drill through the Earth. The first tennis ball breaking the second would be like it breaking through the surface of the Earth. That's what I'm getting from it at least.

 

[siddharth23]

Oh that way.

Well if you know a bit of physics, if you apply a force on an object and the object can apply an equal and opposite reaction force, it won't budge. If your force is higher that what it can provide, it'll move/break.

The the force we apply can easily be countered by the Earth.

But consider the construction of buildings. A strong foundation is built first. If that is not done or if the bearing capacity of the ground is not high enough, the building begins to sink in. Why? Because an equal opposite force cannot be provided by the ground and there is a resultant force in the downward direction.

 

[tarekatpf]

There's a couple of factors at work here, but I think the main one is that objects cannot pass through other objects because there is a repulsive force between them when they touch.

What kind of force is this ''repulsive force''? Is it related to gravitational force? Between which things is this repulsive force acting? And is this single repulsive force between the green and the red ball enough to counteract all the attractive gravitational forces exerted by all the balls between the red and the pink balls?

 

[Naty1]

'Elasticity' is a physical property of materials which return to their original shape after they are deformed. Like a tennis ball or a rubber band for example. They are not very stiff under load. So some stuff 'bounces'.

Dirt is sometimes rather elastic, more so when wet, but tends not to restore while rock tends to shatter rather than deform. All these behaviors result from the chemical bonds of the individual materials.

For one everyday material to penetrate another you need rather a lot of energy, like a bullet, and certain material composition...a 'bubble gum' bullet won't do much, and rubber bullets used by authorities to disperse crowds are fired at lower energy [less gunpowder is used] and deform on impact, so are far less lethal than metal bullets.

A tennis ball does not have sufficient gravitational attraction, not enough force, not enough energy to do much of anything... but bounce. Likewise you sitting on your chair at a computer luckily don't 'drill though the Earth because the gravitational effects between you and Earth are far to weak.

You'd need a lot of gravitational attraction, a lot of force/energy, to overcome the repulsive force Drakkith mentions. The forces holding materials together are in general a lot stronger than gravitational forces at the surface of the earth. And those forces are a lot stronger than you...so push as you might,for example, you can't get your hand to go into a concrete wall.

 

[tarekatpf]

I assume he's asking why gravity does not cause objects to drill through the Earth. The first tennis ball breaking the second would be like it breaking through the surface of the Earth. That's what I'm getting from it at least.

Yep, that's what I'm trying to say. Thanks for helping.

 

[tarekatpf]

I have a strong urge to ask you if you are high on pot :P

Anyways, what exactly mean by 'pulls from the balls' and 'break the balls'?

As far as I understand, according to the law of gravitation, all the things in the universe are attracting each other. In other word, pulling each other. That's what I meant by ''pulls from the balls.''

And by ''break the balls'', I meant due to ''pull from the balls between the red ball and the pink ball'', I thought, the green ball would keep falling down through the red ball, thus breaking the red ball. And then, break the next ball, and then the next, and so on.

 

[tarekatpf]

'Elasticity' is a physical property of materials which return to their original shape after they are deformed. Like a tennis ball or a rubber band for example. They are not very stiff under load. So some stuff 'bounces'.

Dirt is sometimes rather elastic, more so when wet, but tends not to restore while rock tends to shatter rather than deform. All these behaviors result from the chemical bonds of the individual materials.

For one everyday material to penetrate another you need rather a lot of energy, like a bullet, and certain material composition...a 'bubble gum' bullet won't do much, and rubber bullets used by authorities to disperse crowds are fired at lower energy [less gunpowder is used] and deform on impact, so are far less lethal than metal bullets.

A tennis ball does not have sufficient gravitational attraction, not enough force, not enough energy to do much of anything... but bounce. Likewise you sitting on your chair at a computer luckily don't 'drill though the Earth because the gravitational effects between you and Earth are far to weak.

You'd need a lot of gravitational attraction, a lot of force/energy, to overcome the repulsive force Drakkith mentions. The forces holding materials together are in general a lot stronger than gravitational forces at the surface of the earth. And those forces are a lot stronger than you...so push as you might,for example, you can't get your hand to go into a concrete wall.

Thank you very much for your reply. I didn't get this repulsive force though, and I made some questions to Drakkith.

 

[siddharth23]

Repulsive force is the Force of reaction acting on the ball when it falls to the ground.

It's like this. Consider yourself wearing a metallic armour. In front of you is a wall. Behind that wall is Magneto (from X-men).

He tries to pull you towards himself. But the wall stops you at a certain distance. He continues to pull you, like the Earth pulls the ball, but the wall prevents it. The wall will be broken down only when the magnetic force wll exceed a certain limit.

 

[WannabeNewton]

And by ''break the balls'', I meant due to ''pull from the balls between the red ball and the pink ball'', I thought, the green ball would keep falling down through the red ball, thus breaking the red ball. And then, break the next ball, and then the next, and so on.

There is electrostatic repulsion at the microscopic level between the interacting bodies. This repulsion is orders upon orders upon orders upon orders of magnitude stronger than the gravitational interaction.

 

[Drakkith]

What kind of force is this ''repulsive force''? Is it related to gravitational force? Between which things is this repulsive force acting? And is this single repulsive force between the green and the red ball enough to counteract all the attractive gravitational forces exerted by all the balls between the red and the pink balls?

See what WannabeNewton said.

 

[tarekatpf]

Repulsive force is the Force of reaction acting on the ball when it falls to the ground.

It's like this. Consider yourself wearing a metallic armour. In front of you is a wall. Behind that wall is Magneto (from X-men).

He tries to pull you towards himself. But the wall stops you at a certain distance. He continues to pull you, like the Earth pulls the ball, but the wall prevents it. The wall will be broken down only when the magnetic force wll exceed a certain limit.

So is the repulsive electromagnetic force ( as WannabeNewton said ) acting between the outer electrons of the green ball and the outer electrons of the red ball? And if so, is this repelling force between these two balls greater than the pull from all the balls between the red and the pink ball toward the green ball combined?

 

[tarekatpf]

There is electrostatic repulsion at the microscopic level between the interacting bodies. This repulsion is orders upon orders upon orders upon orders of magnitude stronger than the gravitational interaction.

So is the repulsive electromagnetic force acting between the outer electrons of the green ball and the outer electrons of the red ball? And if so, And if so, is this repelling force between these two balls greater than the pull from all the balls between the red and the pink ball toward the green ball combined?

 

[Dale]

So is the repulsive electromagnetic force acting between the outer electrons of the green ball and the outer electrons of the red ball?

Yes.

And if so, is this repelling force between these two balls greater than the pull from all the balls between the red and the pink ball toward the green ball combined?

Yes, otherwise it would break the red ball, as you said.

Consider two protons placed one meter apart. Their gravitational attraction is 1.9E-64 N but their electrical repulsion is 2.3E-28 N, which is 36 orders of magnitude larger. It is very easy for the electrical force to overwhelm the gravitational force.

 

[tarekatpf]

Yes.Yes, otherwise it would break the red ball, as you said.

Consider two protons placed one meter apart. Their gravitational attraction is 1.9E-64 N but their electrical repulsion is 2.3E-28 N, which is 36 orders of magnitude larger. It is very easy for the electrical force to overwhelm the gravitational force.

Thank you very much. I wonder why electromagnetic force is not as ''famous'' as or more so than the gravitational force.

 

[Naty1]

I wonder why electromagnetic force is not as ''famous'' as or more so than the gravitational force.

That's a subjective comparison but the gravitational 'force' is 'famous' [unique] it that it stands distinct and apart from the other three fundamental forces [strong, weak, electromagnetic]. Gravity affects everything whereas the other forces are specific: for example the electromagnetic force is limited to electrically charged particles, like the proton and electron. And gravity is described via a geometrical theory rather than a field theory which has so far made it impossible to mathematically combine gravity with the other three forces in the Standard Model of particle physics.

 

[siddharth23]

Umm for one, it's the gravitational force that keeps us on the Earth.

 

[Nugatory]

Thank you very much. I wonder why electromagnetic force is not as ''famous'' as or more so than the gravitational force.

Some of it is historical, some if it is practical.

The practical reason is that Newtonian gravity is easier to teach and understand without advanced math, so is taught first. Even high-school physics includes a competent introduction to the basic concepts of Newtonian gravity; electricity and magnetism is usually a college-level course. So there's just a lot more people out there who have a nodding acquaintance with gravity; for many people their only experience with how math can be used as a tool for understanding the world is from studying gravity.

The historical reason is that the mathematical formulation of Newtonian gravity was discovered and put to use solving practical problems (ballistic trajectories, falling objects, planetary motion) two centuries before we had an equivalent understanding of electromagnetism.

 

[Nugatory]

Umm for one, it's the gravitational force that keeps us on the Earth.

And it's the electromagnetic force that holds us together - without it we wouldn't have bodies. I'm not sure how far that argument will go.

 

[Dale]

Thank you very much. I wonder why electromagnetic force is not as ''famous'' as or more so than the gravitational force.

Well, they are both definitely in the top ten most famous forces

 

[siddharth23]

Seem to be discrepancies in this argument.

 

[Drakkith]

Seem to be discrepancies in this argument.

Really? Where?

 

[siddharth23]

Participation of electromagnetic force. Maybe there isn't, just that I'm not sure. I'll see if I can find anything.

 

[russ_watters]

Well, they are both definitely in the top ten most famous forces

Just in case anyone didn't get the joke; there are four fundamental forces and I rather suspect that electromagnetism is in the top two "most famous" ( ).

http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html

 

[tarekatpf]

That's a subjective comparison but the gravitational 'force' is 'famous' [unique] it that it stands distinct and apart from the other three fundamental forces [strong, weak, electromagnetic]. Gravity affects everything whereas the other forces are specific: for example the electromagnetic force is limited to electrically charged particles, like the proton and electron. And gravity is described via a geometrical theory rather than a field theory which has so far made it impossible to mathematically combine gravity with the other three forces in the Standard Model of particle physics.

Sorry for the late reply. I didn't know there's a page 2 in this thread, since this is only my second post on the physics forum.

And thanks for your reply.

Does this gravity affect protons and electrons too?

 

[tarekatpf]

Some of it is historical, some if it is practical.

The practical reason is that Newtonian gravity is easier to teach and understand without advanced math, so is taught first. Even high-school physics includes a competent introduction to the basic concepts of Newtonian gravity; electricity and magnetism is usually a college-level course. So there's just a lot more people out there who have a nodding acquaintance with gravity; for many people their only experience with how math can be used as a tool for understanding the world is from studying gravity.

The historical reason is that the mathematical formulation of Newtonian gravity was discovered and put to use solving practical problems (ballistic trajectories, falling objects, planetary motion) two centuries before we had an equivalent understanding of electromagnetism.

I wonder how Newton explained this phenomenon since the electromagnetic force wasn't discovered then yet. Didn't this question occur to him that without some kind of very very very strong repulsive force, things would be piercing the whole planet?

 

[tarekatpf]

Well, they are both definitely in the top ten most famous forces

Along with ''the Force'' from the Star wars perhaps?

 

[tarekatpf]

Participation of electromagnetic force. Maybe there isn't, just that I'm not sure. I'll see if I can find anything.

I wonder how whether electromagnetic force really existed when the planet started to form. Because the planet must have started with two atoms or something attracting each other.

Didn't the outer electrons of those first two atoms repel each other, since the gravity was way weaker than the electromagnetic force?

Was the condition different then? Like superhigh temperature or something?

 

[Nugatory]

I wonder how Newton explained this phenomenon since the electromagnetic force wasn't discovered then yet. Didn't this question occur to him that without some kind of very very very strong repulsive force, things would be piercing the whole planet?

Well, he's not around to tell us what he was thinking... But it is safe to say that in the 17th century people mostly took the solidity of objects for granted, as a self-evident proposition needing no explanation; some materials, such as water, are just more penetrable than others, like steel. I expect that Newton and his contemporaries were no more perplexed by the fact that a brick would sit on the surface of the Earth instead of piercing through it, than they were by the fact that a heavy sledgehammer blow would bounce off of it. (And it's worth noting that the forces involved in a sledgehammer blow are much greater than that of gravity acting on a brick).

 

[Nugatory]

I wonder how whether electromagnetic force really existed when the planet started to form. Because the planet must have started with two atoms or something attracting each other.

Didn't the outer electrons of those first two atoms repel each other, since the gravity was way weaker than the electromagnetic force?

Although gravity is a very weak force, it has one advantage over electromagnetism: All particles attract gravitationally, while with electromagnetism there are positive and negative charges, and like charges repel.

A hydrogen atom (for example) is made up of a positive-charged proton and a negative-charged electron. If you get any significant distance away from the atom, it is electrically neutral; the electrical force exerted by the proton will almost completely cancel out the electrical force exerted by the electron. But the gravitational force is still there. Thus, if you have a large number of hydrogen atoms floating around in empty space, their gravitational attraction will tend to pull them together no matter how spread out they are; the electromagnetic forces won't be significant until the atoms are so close that they are starting to bump into one another.

 

[Nugatory]

Does this gravity affect protons and electrons too?

Yes. Look at DaleSpam's post #16 in this thread.

 

[tarekatpf]

Although gravity is a very weak force, it has one advantage over electromagnetism: All particles attract gravitationally, while with electromagnetism there are positive and negative charges, and like charges repel.

A hydrogen atom (for example) is made up of a positive-charged proton and a negative-charged electron. If you get any significant distance away from the atom, it is electrically neutral; the electrical force exerted by the proton will almost completely cancel out the electrical force exerted by the electron. But the gravitational force is still there. Thus, if you have a large number of hydrogen atoms floating around in empty space, their gravitational attraction will tend to pull them together no matter how spread out they are; the electromagnetic forces won't be significant until the atoms are so close that they are starting to bump into one another.

Thank you very much again for your answer.

I have this question now.

Wouldn't the repulsive force exerted by the outer electrons of the red ball ( which represents surface of the Earth ) neutralized by the pull from the protons of the red ball? Then how come the red ball's outer electrons still repel the outer electrons of the green ball ( the repulsive force of the outer electrons would be neutralized by the protons of the green ball too, I think. )

 

[siddharth23]

The answer is reactive force.

 

[tarekatpf]

The answer is reactive force.

I am sorry I did not get which question you're referring to, since I have made a lot of questions.

 

[Drakkith]

Thank you very much again for your answer.

I have this question now.

Wouldn't the repulsive force exerted by the outer electrons of the red ball ( which represents surface of the Earth ) neutralized by the pull from the protons of the red ball? Then how come the red ball's outer electrons still repel the outer electrons of the green ball ( the repulsive force of the outer electrons would be neutralized by the protons of the green ball too, I think. )

(Very very simplified explanation)
No, the electrons of each atom are separated from the nucleus and "touch" each other first. Since the electrons are closer to each other they experience a repulsion. There is also charge screening going on, which is when the charge from the nucleus is screened from being felt by anything outside the atom.

 

[tarekatpf]

(Very very simplified explanation)
No, the electrons of each atom are separated from the nucleus and "touch" each other first. Since the electrons are closer to each other they experience a repulsion. There is also charge screening going on, which is when the charge from the nucleus is screened from being felt by anything outside the atom.

So, suppose I have two atoms. Atom A and Atom B. Centrifugal forces of all the electrons of Atom A are canceled out by centripetal force of all the protons of the Atom A.

Now if I bring atom B, why would the outer electrons be repelled by the outer electrons of atom A? Has any ''new force'' generated spontaneously?

 

[Nugatory]

I have this question now.

Wouldn't the repulsive force exerted by the outer electrons of the red ball ( which represents surface of the Earth ) neutralized by the pull from the protons of the red ball? Then how come the red ball's outer electrons still repel the outer electrons of the green ball ( the repulsive force of the outer electrons would be neutralized by the protons of the green ball too, I think.)

That is indeed the natural next question... and we're getting to where we actually have to play with the math to see how it supports intuition. Here's a fairly simple model that illustrates the underlying physics pretty well.

Imagine that a hydrogen atom consists of one electron and one proton, connected by a rod of length 10^-12 meters. The total electrical force on the the atom from any nearby charged particles can be calculated just by adding the force on the proton and the force on the neutron. We'll make life a bit easier by choosing units in which the charge of the electron is -1 and the charge of the proton is +1 so the force between two particles is $\frac{1}{r^2}$, attractive or repulsive according to the signs of the charges.

Now consider two such atoms lined up on the x-axis with their electrons facing each other, and 1 meter apart measuring proton to proton. What's the total force on the left-hand atom from the electrical particles in the right-hand atom?
1) The protons repel each either with a force of $\frac{1}{r^2} = \frac{1}{1} = 1$
2) The electrons repel each either with force of $\frac{1}{r^2} = \frac{1}{1-(2\times10^{-12})^2} \approx 1-2\times10^{-24}$
3) The left-hand electron and the right-hand proton attract with a force of $\frac{1}{r^2} = \frac{1}{1-(10^{-12})^2} \approx 1-10^{-24}$
4) The left-hand proton and the right-hand electron attract with a force of $\frac{1}{r^2} = \frac{1}{1-(10^{-12})^2} \approx 1-10^{-24}$

Add the two attractive and the two repulsive force and you get... zero, give or take some corrections that are small compared to $10^-24$ from the approximations in #2, #3, #4 above. There's just no detectable attraction or repulsion.

Now consider what it looks like if we try to push the two atoms together so that the electrons are touching and the protons are separated by just $2\times{10^{-12}}$ meters. The repulsive force between the protons is now stronger, as is the attractive force between the proton-electron pairs. But none of these matter, because the the repulsive force between the electrons is $\frac{1}{0^2}$ which is infinite! This tells us that we can't actually push the two atoms that close together - if we try the total force will become ever more strongly repulsive as we push them closer.

 

[tarekatpf]

That is indeed the natural next question... and we're getting to where we actually have to play with the math to see how it supports intuition. Here's a fairly simple model that illustrates the underlying physics pretty well.

Imagine that a hydrogen atom consists of one electron and one proton, connected by a rod of length 10^-12 meters. The total electrical force on the the atom from any nearby charged particles can be calculated just by adding the force on the proton and the force on the neutron. We'll make life a bit easier by choosing units in which the charge of the electron is -1 and the charge of the proton is +1 so the force between two particles is $\frac{1}{r^2}$, attractive or repulsive according to the signs of the charges.

Now consider two such atoms lined up on the x-axis with their electrons facing each other, and 1 meter apart measuring proton to proton. What's the total force on the left-hand atom from the electrical particles in the right-hand atom?
1) The protons repel each either with a force of $\frac{1}{r^2} = \frac{1}{1} = 1$
2) The electrons repel each either with force of $\frac{1}{r^2} = \frac{1}{1-(2\times10^{-12})^2} \approx 1-2\times10^{-24}$
3) The left-hand electron and the right-hand proton attract with a force of $\frac{1}{r^2} = \frac{1}{1-(10^{-12})^2} \approx 1-10^{-24}$
4) The left-hand proton and the right-hand electron attract with a force of $\frac{1}{r^2} = \frac{1}{1-(10^{-12})^2} \approx 1-10^{-24}$

Add the two attractive and the two repulsive force and you get... zero, give or take some corrections that are small compared to $10^-24$ from the approximations in #2, #3, #4 above. There's just no detectable attraction or repulsion.

Now consider what it looks like if we try to push the two atoms together so that the electrons are touching and the protons are separated by just $2\times{10^{-12}}$ meters. The repulsive force between the protons is now stronger, as is the attractive force between the proton-electron pairs. But none of these matter, because the the repulsive force between the electrons is $\frac{1}{0^2}$ which is infinite! This tells us that we can't actually push the two atoms that close together - if we try the total force will become ever more strongly repulsive as we push them closer.

I didn't understand some of your maths.

Shouldn't the force exerted on the electrons of the left hand atom by the right hand atom's electrons be [1 / { 1- ( 2 x 10^-2 ) }^ 2 }] ? Since the distance between two electrons should be { 1- ( 2 x 10^-2 ) }, and the force should be 1/ (distance)^2?

( I don't know how you put those mathematical symbols there? Could you please help me? )

Similarly, shouldn't the attractive force between the electrons and protons of opposite side be ( 1- ( 10^-2) )^2 ?

Please correct me if I am wrong.

 

[Nugatory]

( I don't know how you put those mathematical symbols there? Could you please help me? )

It's documented here: https://www.physicsforums.com/showpost.php?p=3977517&postcount=3

 

[Nugatory]

Shouldn't the force exerted on the electrons of the left hand atom by the right hand atom's electrons be [1 / { 1- ( 2 x 10^-2 ) }^ 2 }] ? Since the distance between two electrons should be { 1- ( 2 x 10^-2 ) }, and the force should be 1/ (distance)^2?

Look carefully - I set the separation to 10^-12 not 10^-2.

BTW, I did get a sign wrong. It should be
$\frac{1}{r^2} = \frac{1}{1-(2\times10^{-12})^2} \approx 1+2\times10^{-24}$
(note the $+$ sign in the rightmost term) but that doesn't change the result: the net force is negligible when the atoms are separated by one meter, but very strong when they are s close to one another that the electrons are almost touching.

 

[adi19956]

First of all, I want to say that I am totally ignorant about physics. And I do not understand the general concepts of physics at all.

Now coming to the question.

Suppose, you drop a green tennis ball from above.

Now It usually lands on Earth and stop there ( ignore the bounces for now. ) Suppose, the point at which the green ball lands is a red ball. Since the Earth is made of ''a mass of balls'' ( to get the concept, I am using such metaphors ), below the red ball should be another ball, and below that another ball, and so on, till you reach the opposite point on the earth, which is, suppose, a pink ball.

Now since all the balls from the red ball upto the pink ball is drawing the green ball toward them, how can this one little green ball stop just over the red ball ignoring the pull of all the balls between the red and the pink one?

Shouldn't it just ''break the red ball'' and keep reaching toward the next ball and break that too? I mean, drilling through earth?

I know the Earth is more or less a sphere. So are the pulls from balls around the red ball preventing the green ball from drilling through earth?

Did you post this on The Student Room?

 

[tarekatpf]

Look carefully - I set the separation to 10^-12 not 10^-2.

BTW, I did get a sign wrong. It should be
$\frac{1}{r^2} = \frac{1}{1-(2\times10^{-12})^2} \approx 1+2\times10^{-24}$
(note the $+$ sign in the rightmost term) but that doesn't change the result: the net force is negligible when the atoms are separated by one meter, but very strong when they are s close to one another that the electrons are almost touching.

Sorry, that should indeed be -12, not -2. But let me show in a diagram what I thought:

I didn't understand why you think the force with which the electrons repel each other is [1 / { 1- ( 2 x 10^-2 )^2 }] instead of [1 / { 1- ( 2 x 10^-2 ) }^ 2 }]

 

[tarekatpf]

Did you post this on The Student Room?

Yes, why?

 

[adi19956]

Yes, why?

I saw it there too, weird

 

[Nugatory]

instead of [1 / { 1- ( 2 x 10^-2 ) }^ 2 }]

Because I still can't type .

It is, of course and as your picture shows, $\frac{1}{(1-2\times{10^{-12})^2}}$ for the electron/electron repulsion, $\frac{1}{(1-{10^{-12})^2}}$ for the electron-proton attractions, and $1$ for the proton-proton repulsion.

The result of the arithmetic comes out the same though: when the atoms are separated by one meter the net force between them is negligible because all the forces are equal to one, give or take some tiny correction; but as you push them closer together the electron-electron repulsion dominates.

 

[brocks]

Thank you very much. I wonder why electromagnetic force is not as ''famous'' as or more so than the gravitational force.

Because most people are not physicists. EM forces and fields are a large part of a physics curriculum.

But you have seen how much stronger electromagnetic forces are than gravity, you just didn't realize what you were seeing. Most kids have seen that if you get a small static charge on a comb or balloon or something by rubbing it on their hair, you can pick up bits of paper with it. The paper is being drawn down by gravitational force of the entire earth, and it's being lifted by the measly little static charge on your comb. And the comb wins.

 

[tarekatpf]

Because I still can't type .

It is, of course and as your picture shows, $\frac{1}{(1-2\times{10^{-12})^2}}$ for the electron/electron repulsion, $\frac{1}{(1-{10^{-12})^2}}$ for the electron-proton attractions, and $1$ for the proton-proton repulsion.

The result of the arithmetic comes out the same though: when the atoms are separated by one meter the net force between them is negligible because all the forces are equal to one, give or take some tiny correction; but as you push them closer together the electron-electron repulsion dominates.

Thanks for your great and kind efforts. Your mathematical explanation really helped me a lot.

Thanks, again.

 

[tarekatpf]

Because most people are not physicists. EM forces and fields are a large part of a physics curriculum.

But you have seen how much stronger electromagnetic forces are than gravity, you just didn't realize what you were seeing. Most kids have seen that if you get a small static charge on a comb or balloon or something by rubbing it on their hair, you can pick up bits of paper with it. The paper is being drawn down by gravitational force of the entire earth, and it's being lifted by the measly little static charge on your comb. And the comb wins.

Yep. A classic example. Thanks.