exchemist

Are we all barking up the wrong tree because of your initial choice of term for the machine you have mind? Are you perhaps thinking of a hydraulic intensifier: https://en.wikipedia.org/wiki/Hydraulic_intensifier ?

Haha, I did wonder if you were a closet free energy crank, what with all your talk of being banned and everything. Can you refer me to a link to this 1900 fellow? Clearly he wasn't quite as smart as all that - or maybe he wanted to pull a few people's legs. Like you perhaps.

Well, you still need to induce the water to freeze, of course. And the freezing point will be depressed by the pressure, because the pressure will shift the point of equilibrium between water and ice. So you will need a colder fridge.

Er, not quite. Chemical energy is converted into work as well as heat, as the bonds form during crystallisation. But it would indeed mean less heat for the refrigeration to remove, yes.

It's because you don't understand the science and make statements that are not credible, I expect. It looks to me as if we need to talk a bit about enthalpy, H. Enthalpy, H=U +PV, where U is the internal energy of a system and PV is the work done done on, or by, the system due to its expansion or contraction under any prevailing pressure during changes to the system. In chemistry we generally work with enthalpy because most chemical reactions are carried out at atmospheric pressure. So any changes in volume during a reaction will either push back the atmosphere (if the reacting system expands) or get pushed on by the atmosphere (if it contracts). These effects alter the total amount of energy measured as coming out or going into the reaction system. So, in the case of ice freezing, Latent Heat of Fusion comes out of the water as it freezes. If the system is open to the atmosphere, the amount of heat that comes out will be a bit less than if the water was being frozen under vacuum. That's because some of the internal energy released, as the bonds in the ice crystal form, goes into pushing back the atmosphere as the ice expands. In a vacuum there is no work done, so all the internal energy from bond formation comes out as Latent Heat. If you now put the water in a cylinder underneath a huge weight and freeze it, the heat that comes out during freezing will be less still, because more of the internal energy in the forming bonds goes into pushing up the weight. So in summary, there is a fixed amount of internal energy, per gram - per molecule, in fact - that is released when ice forms. How much comes out as Latent Heat depends on the PV work the water has do as it freezes. There is no free lunch here.

No.

I can't do this in these silly units, but if the pump can generate a certain pressure you just need to make sure your system does not require a greater pressure to lift whatever it is you want to lift. Force is pressure x area, so with enough area you can produce any force you want. The catch of course is the rate of lifting, in terms of vertical distance lifted, goes down as the area goes up, because the pump can only introduce fluid at a fixed rate, so the bigger the area the slower it lifts.

No. I'm getting fed up with you now. Reported.

Some of us were talking before your mum and dad were born, I imagine. But you are replying to an 18 year old thread, with a rather pointless post. If you do that, people will think you are an internet robot or something.

Well in that case you won't get any "explosion", will you? The piston will gently move out by 9% as the water freezes and, er, that's it. It can be made to do the same amount of work as your earlier ice bomb explosion, of course, but just in a less dramatic way. Correction: Sorry I see you propose something that makes it go ping when the pressure has built up. Not sure what advantage that has, but fair enough, it will go ping, then.

OK, but it stretches a bit. What happens is you stretch it beyond the elastic limit, reach the yield point and then it fails.

There are a lot of anti-vaxxers and nutjobs about at the moment, as you may be aware, that like to cast doubt on the safety and efficacy of vaccination. It looks as though some of the people here have got burnt by this in the past and may have thought you could be one of them, rather than just someone who is not well informed. Risks from the vaccines are small compared to the risks from the disease, even for younger people. Aside from the risk of death or emergency hospitalisation if you are fat, there's a lot of long Covid about. I have a nephew who is very fit (got a half blue at Oxford, rowing for the Lightweights), whose sense of taste has been permanently altered by the virus. I lost my sense of taste and smell totally for a fortnight, which became a bit frightening, though luckily it has come back. The risk of blot clots with the Oxford/AstraZeneca one seems to be about one in half a million: about a fiftieth of the annual risk of blood clots run by a woman on the pill. Nevertheless for those under 40, it is recommended to get one of the other vaccines if possible, for preference, just to avoid even this small risk. As others have pointed out, by getting vaccinated you also help reduce the incidence of Covid in the population as a whole, which reduces the chance of more, nastier, mutations coming along and setting us all back to square one. So yes, get vaccinated. I had my second shot last week (AstraZeneca).

I'm not sure I follow this. It looks as if you envisage a closed container that stretches and then suddenly bursts from the pressure of the ice and that this moves a piston. Depending on what load the piston is connected to, I suppose with a light load it might fly away from contact with the ice, leaving a near-vacuum behind. It won't be quite a vacuum as there will be the vapour pressure of water or ice at 0C present - about 4.5mmHg, so not much, admittedly. A vacuum won't cause the ice to melt. Many comets are made of ice. So there won't be any boiling. Why is this piston "gigantic", suddenly? Are you smoking exotic cheroots? 😀

I think we should leave urinary infections out of this. 😆

Strictly, yes of course, but the way this problem has been posed, you don't actually need the sign to get the right answers.

Eh? Lifting weights expands nothing. Work done in expansion is PdV. Think of it this way: if you have an expanding fluid pushing a piston, the work done is the force, F, on the piston (pressure x surface area) multiplied by the distance, d, the piston travels - which is volume change/surface area. So Fd = PA x ΔV/A = PΔV. (Since P is likely to change as V increases you need to do it as an integral, hence ∫PdV. ) So expansion volume certainly is the determinant, along with pressure, of the available energy.

The expansion on freezing is only about 9% volume, so the work done in expansion when the pressure is released is not that much - enough to bust the container but not much more. There is very little stored energy. You get a lot more stored energy in compressed gases than you do in compressed liquids and solids, because gases expand to many times the confining pressure, doing a lot more work (= energy). That's why heat engines rely on gases.

Aha! Now the rest of your calculation makes sense! I see where you get the deceleration of 2m/sec² from (12m/sec -> 4 m/sec over 4 seconds)and given that the mass is 0.5kg, that will imply a force of 1N, just as you say. So it all looks good to me.

OK. I have however one specific piece of immediate advice for you: learn to use full stops. 😀

These are only "fundamental questions of physics" if the questions have a meaning. And they only have a meaning in physics if they predict some observable result. This is where I struggle. I cannot see what observational outcomes can be dependent on this shape issue of yours. A photon is either detected, by absorption in an atom generally, or they are not. Isn't it?

Where do you get this stuff from about the limits of pumps? And why choose the worst possible type of pump for dealing with big pressure differences? You would need a +ve displacement pump, not a centrifugal one. Injector pumps can manage well over 500bar. And surely by a 2-stage process you could reduce the stresses between each stage considerably, couldn't you?

I'm not sure the "width" of a wavepacket tells you anything about the size of a photon. Surely it just tells you the shape of the probability distribution of where you may expect to detect it, doesn't it? And QM tells you that anyway, so there is no issue there. Whatever it is you are after must be something different, or we would not be having this discussion.

I can't say I had ever come across them, until a few years ago on the internet. Anyway, it's nice to know one can always annoy them by asking if it is true that the Flat Earth Society has members all around the globe. This seems to be a meme they can't kill off.

You do not say how old you are, but you could perhaps start with something like this: https://www.ducksters.com/science/chemistry/. If it's the wrong level let me know and I'll try to find something else. Also, if you are interested in chemistry you can learn a lot by looking at things in the Periodic Table. Here is one I use, that links to Wikipedia articles on each element and is quite informative: https://ptable.com/#Properties Obviously, people on a discussion forum are not going to be able to provide a course on-line just for you. That would be a lot of work. We can maybe help you with specific issues, though, as you encounter them.

I'm going to start by saying I'm a mere chemist who learnt some quantum chemistry 40 years ago, so I am not an authority. However I have read a bit about this, as I found it confusing. What follows is my understanding. I'm also going to ignore the instruction to start with yes or no, as I think you pose a bit of a false antithesis. Sorry. I have to take issue with your assumption that to be force carriers these entities need to be "pockets of energy". I think that is wrong at at least two levels. First, energy is not stuff: you can't have a jug of energy. Energy is a property of a system of some kind. Things "have" energy. They can't "be" energy. Second, I think it is wrong to imagine that virtual particles need to have energy in order to be force carriers. An entity does not have to experience energy gain or loss to experience a force. As to whether virtual particles are "real", I'm going to risk annoying you by saying I think it depends what you mean by "real". What seems to be the case is that virtual particles are not particles. They are - so I gather - disturbances in various fields that can be modelled using some of the same mathematics as particles. But the disturbances in the field are "real", in that there are observable consequences of them. A year or two ago I came across a very good article about virtual particles by Matt Strassler, here, which may help you. It helped me, anyway: https://profmattstrassler.com/articles-and-posts/particle-physics-basics/virtual-particles-what-are-they/