Recent content by f91jsw

You are right of course. I think my main argument was trying to bracket the equilibrium state between extremes. The extremes being pure water/pure CO2 on one end, totally dissolved CO2 on the other. Neither of these states are obviously stable. Somewhere between these two states there will be an...

One could also argue the exact opposite: in the zones of greater pressure the gas will dissolve in the liquid. Which effect wins? Will there be a net change? /J

If you accept that we start in a state of thermodynamic equilibrium the entropy would decrease by definition. /J

Entropy argument: let's assume we have a situation where we have a sealed container where one part of the volume is occupied by pure water and the remaining part is occupied by pure CO2 at a certain pressure. If we now wait for a sufficiently long time the system will reach an equilibrium state...

The web page you quote implies that carbonated beverages are supersaturated solutions of CO2 at atmospheric pressure, which is correct. At the elevated pressure in the unopened can I would argue that it is not supersatured. I guess it depends on how you define "supersaturated." Obviously a...

The prerequisite of this whole discussion is equilibrium, i.e., no supersaturated system. So I can't see how your argument can be valid. /J

I've tried it on (plastic) Coke bottles now. Still can't feel any difference. Are you sure you can feel a difference or are you just making that assumption? /J

I think no one is disputing how the experiment would be done. I have done it on unopened cans and I can't feel any difference. I don't see what using half-emptied bottles would add. Since nobody has produced any experimental or theoretical evidence otherwise the preliminary conclusion must be no...

Initially of course the pressure will increase, until a new equilibrium is reached, that's trivial. My question was, does the pressure increase after equilibrium has been reached if you shake the bottle? /J

The first question is, does it really change from dissolved to gaseous? The first thing we have to establish is whether it really does and whether the pressure actually increases. I just made a little experiment using 4 cans of beer. I shook two of them. Then I tried to feel if there was any...

The explanation for why it explodes is that shaking will cause a lot of microscopic bubbles in the liquid. When you open it these bubbles will want to expand. There is no need for an increase in pressure in this picture which is why it is not "obvious" at all that the pressure would increase. /J

If you shake an (unopened) soda can or bottle, will the pressure inside increase or stay the same? If it does increase, what is the mechanism? Assumption: the soda has been at constant temperature for a long time. (please don't answer "of course it increases" just because the soda explodes...

From an experimental point of view a photon is what causes a "blip" on a photon counting detector as you shine (low intensity) light on it. Johannes

I'm not a physics teacher, I just teach physics between doing physics research (in the UK). The problem formulation did not state that the plane was starting from a sand trap or that the wheels were locked. You can't invent new circumstances to save your theory. BTW, hint: look up a...

This thread has definately dragged on for way too long for a physics forum. The simple answer is: The plane will take ALWAYS take off NO MATTER WHAT SPEED the conveyor belt moves with. For those who can't see it intuitively it's simple Newtonian physics: The engines produce thrust, which...