What you mean by "the ground" is the surface at which the Coulomb repulsion - and that due to the Pauli Exclusion Principle - prevent any further approach of the atoms of an object supported by it. In fact, the greater the pressure, the closer the atoms do get, slightly, due to the ground and the object getting a bit compressed, i.e. their atoms moving close enough for the Coulomb and Pauli repulsions to increase further, enough to support the greater weight.
Not really. The electrons in the material of the ground do not 'touch' the electrons of the rocks, but to say the rock is floating gives a very misleading picture. Just by simply considering that there is friction between the ground and the rock will tell you that the rock is not floating. This is due to the always rough surface of the ground and the rock. So you might think, well if the surfaces were extremely smooth then the rock would float above the ground. However this is wrong. If you polish most materials to a very smooth surface and mate them together they will not float at all they will stick together. They stick together due to inter-molecular forces and surface tension. This concept is used to mate gage blocks together in a process called wringing. Holding two magnets together in a N to N configuration neither negates the repulsive 'potential' nor makes the force 'latent'. Holding the magnets together merely means that the force of you holding the magnets together overcomes the force of repulsion, it is just that simple.
Is the Pauli exclusion principle based on Coulomd law? That is what I understood, but does that not involve an increase in energy Does that involve an increase in energy?
The Pauli exclusion principle is unrelated to electric charge. It is an exchange interaction and results from the operation of Fermi-Dirac statistics, which apply to QM entities with half integer spin (known as"fermions"), preventing any two entities from occupying the same quantum state. More here: https://en.wikipedia.org/wiki/Exchange_interaction And yes, of course compression does work on the system and thus gives it potential energy, which is released when the pressure is removed. But if the material is relatively incompressible, the amount of work done (=F x d) is small.
Since the rock is in equilibrium, sitting on the ground (separated by electron repulsion), there is no net usable energy. If you were to press down on the rock, it would get atomically closer to the ground - because you added an outside force. If you let go, the rock could rebound atomically, releasing that energy. You're still overthinking it. What I mean by this is that this potential energy versus kinetic energy is a macroscopic process; the details at the atomic level don't matter. It doesn't matter whether you consider two atoms bumping together as if they are physical spongy balls, or whether you consider two atoms bumping together as energy fields. The difference is entirely semantic to the issue of potential/kinetic energy transfer.
exchemist #27; Gravity is always on. Objects are accelerated toward the center of the earth. The ground interferes with their motion, absorbing their momentum. If you place a scale between the object and the ground, it will measure a force (mg=weight), thus the object is still accelerating, and the energy is dispersed as heat.
That would literally be free energy (and an infinite amount of it, too!), so no, that obviously can't be true. And turns out it isn't, because no work is being done, so no energy is being transformed/used/expended.
Complete rubbish from start to finish. If that were true you could extract an infinite amount of heat from the table in your kitchen, just by leaving it standing there. Don't be an idiot.
No. No. No. Unless you mean that the energy expended to move the magnets together is equal to the potential energy now in the system. If you let go of the magnets they will convert that potential energy to kinetic when they move apart. But that is obvious, right?
And, in contact with the ground, their velocity becomes zero, their momentum is zero. As is their ability to do work. Just no.
Why is the Coulomb law mentioned in relation to a person not falling throught he floor.? After all there is always more space than matter between surfaces , polished or not. Please Register or Log in to view the hidden image! Magnetism? OTOH, Please Register or Log in to view the hidden image! What is the functional difference between the two forces (states)?
That has nothing to do with your question: "Is the Pauli exclusion principle based on Coulomd law?" The answer to that is still no. WTF? I am amazed that you actually asked the question. The answer to your question is what you posted just above your question!! Bizarre?!?Please Register or Log in to view the hidden image!
I just want clarification. Is it too complicated to explain in a few words or reference to a link? TY, I'll need to dig into that to understand the fundamentals. I did notice the mention of the Coulomb force as somehow being tangently related, but I'll need to study this more. One conclusion seems important (bracketed insert "Coulomb force" mine). Am I on the right track here?
NO. This shows the danger of picking bits out of context from the complicated parts of articles you have not understood first. The passage you refer to is speaking about J(ab), which is a derived quantity, expressing the effect of spin on energy and includes both a contribution from the Coulomb interaction and one from the exchange interaction. Stick to the 1st para. The fact that two fermions cannot occupy the same quantum state increases the average distance between two particles when there is spatial overlap between their wavefunctions: in effect the particles repel one another. The first para states it has no classical analogue. So it is neither an electrostatic nor a magnetic phenomenon.
TY. The problem is that at first (layman's) glance there seems to be a contextual relationship. I got the term Coulmb force from a link that explains the phenomena why we do not fall trough the floor. Perhaps that link was incorrect. I wish I had saved it. Can't find it anymore. I'll just have to work my way through......Please Register or Log in to view the hidden image!
Well one can think of the effective "size" of atoms as due to the repulsion between neighbouring electrons when one atom is squashed against the next. And that is why, if you like, we don't fall through the floor. Atoms are mostly empty space, so what determines their "solidity" is this resistance to compression. A simplistic treatment of that would simply refer to Coulomb repulsion: not every schoolchild is ready for the Pauli Exclusion Principle and Fermi-Dirac vs. Bose-Einstein statistics. Maybe I should not have mentioned exchange interactions if it leads to confusion.
In a real world process, the moon orbits the earth. The velocity of the moon has 2 components, speed and direction. Energy is required to change either component. What is the source of energy that changes the direction of the moon's orbit to maintain an approximately constant distance from the earth? Why does NASA program 'sling shot' maneuvers for some space probes as they pass a large mass? Why does an object fall to earth when released at any altitude above the surface of the earth? The answer is the same for all 3 cases, free gravitational energy. GR states, the g-field depends on the distribution of matter, thus remove the mass and remove the g-field. The mass is the source of energy which forms the g-field, in a currently unknown process. An object placed in the field is immediately affected with an increase in kinetic energy. An object in your hand requires energy to hold it at a given height, producing fatigue resulting from physical exertion, an expenditure of energy, yet there is no motion of the object relative to the ground. This is a critical difference between SR and GR. In SR available energy is confined to a closed system, a spaceship, lab, etc. In GR available energy extends to any large mass, which removes the limitation of acceleration as in SR Infinity is not a quantifier, and most misuses of the word are nonsensical. Gravitational force is extremely weak, especially for sand grains, so thermal activity would not be sufficient to cook your dinner on the table top.
This is wrong. There is no energy required to maintain a body in circular motion at constant angular velocity. Taking the moon to be in a circular orbit, it is at constant radius from the earth and thus its gravitational potential energy is not changing. Furthermore its speed is constant and therefore its kinetic energy (=1/2. mv²) is also constant. Bear in mind that although v is a vector quantity, with direction as well as magnitude, energy is a scalar. So a change of direction of velocity does not necessarily imply a change in kinetic energy. (The same applies to a train rounding a curve in the track. The rails are able to change the direction of motion with almost no change in kinetic energy.)
Write4U: Because the force of gravity is pulling the person towards the centre of the Earth, and the only force that prevents him or her falling to there is the force of electrical repulsion between atoms in his or her feet and atoms in the floor. Yes, but the "empty" space doesn't matter. Only the amount of force that is exerted matters. Electrical forces increases as charged particles get closer together. There is more than enough available electrical force to stop a person falling through the floor, despite the "empty" spaces between atoms in his or her feet and between atoms in the floor. Moreover, the electric force is vastly stronger than the gravitational one, under normal circumstances. The Pauli exclusion principle, roughly speaking, prevents electrons in an atom from occupying the same space at the same time. Imagine if the Pauli principle didn't exist. Then, all the electrons in an atom would still be attracted electrically to all of the positive charge in the nucleus. The lowest energy state would correspond to all of the electrons orbiting at the same distance from the nucleus. There would be no chemistry, since every kind of atom, whatever the element, would have all of its electrons in essentially the same place in the atom. The Pauli principle has nothing to do with the electric force, or with electrical charge. Fundamentally, it has to do with intrinsic spin of the electrons.
