swansont

It puts the treatment on equal footing. I don’t understand this reasoning. c is a proportionality constant; this situation is present throughout physics. Constants can be large or small. If you double the time, you double ct. That variation is the important thing. It’s not a tiny factor. If t doesn’t change, the dependent variable doesn’t change.

! Moderator Note Not a whole lot of discussion of the OP, and multiple hits on what we consider arguing in bad faith. Closed, and don’t bring either the geology or the physics of this tangent up again. This is a science discussion site, not Rants-R-Us

! Moderator Note You’ve been told before that this posting style is contrary to the rules (2.7) “Attached documents should be for support material only; material for discussion must be posted. “

It’s true that if you did an “aborted jump” and ended on your toes the scale reading would go down, the description is not consistent with saying the force never exceeds the static value - it should be larger than that during the earlier time that the CoM is rising.

You wrote what was in your post. I quoted it and I moved it; I did not edit it. You were notified because it was a hijack of the discussion.

This makes sense to you. The absence of light - literally no photons - is a physical object. The dirt in a hole is a physical object, and not having that dirt is also a physical object. Defining everything as a physical object makes it simple, I guess. Gravity is an interaction, not an object. Same with magnetism.

That’s circular reasoning. it’s physical because I can measure it, and I can measure it because it’s physical. I can measure a shadow or a hole. Are these physical objects? It’s a simple, independent criterion. Because concepts are not physical objects.

Yes, I can give you a photon. Just one would be difficult for technical reasons, not philosophical ones. Length and time can be measured. Neither is a physical object.

Can you hand me a volume of space? Geometry is not a physical thing, and when we say spacetime has a geometry, it’s saying there’s a particular coordinate system that is best suited to describe it. e.g. the shortest distance between two points is a straight line or a specific curve.

It doesn’t, if the scale works by measuring the normal force.

Unless you define that to be up. It’s a label and it’s arbitrary. (with the caveat that one needs to label in a consistent fashion)

But these are not physical things unto themselves.

I’m giving a scenario which maximizes the CoM motion, to show how your explanation can’t be correct. The momentum is taken up by the earth, not the scale (to first order). The scale does compress, and more than if you were just standing on it - that part is correct. But if it compresses more, the reading has to go up.

So if you’re 60 kg, and the scale is 1 kg, you’re saying the scale mechanism is moving 60x faster than you are. Does that seem reasonable? You bend your knees and then we start the exercise: you straighten up, moving ~1m, in 2 seconds. How can the scale compress at 30 m/s for 2 seconds?

There is no F=ma exception for flesh or bone

! Moderator Note This not your thread. Split from https://www.scienceforums.net/topic/120896-a-mass-can-be-be-lifted-with-force-less-than-its-weight/

But does math exist?

Concepts don’t exist?

Then you can put it anywhere you like, but I think it needs to be rigid If it’s glass there’s no compression. The glass provides the force on the water. But you can observe what 20m of water would do to visibility, since we have situations like this. Things would be very blue https://www.researchgate.net/figure/Penetration-of-Light-of-Various-Wavelengths-through-Water-Blue-Light-is-the-Strongest_fig3_220785640 http://oceanography-leahmoore.blogspot.com/2010/10/light-attenuation-for-various-colors-of.html

That amount of water, as vapor, is my take. I'm going to answer a slightly different question, to start (there are so many ways the scenario is just impossible). Let's assume we have 1 square cm of surface. 10 meters of water is 1000 cm, so we have 1000 cm^3, or 1 liter (mass of 1 kg). We're going to vaporize this by raising the temperature and then boiling it. To heat it up to boiling requires 4184 J/kg per ºC. If we start at 20ºC, that's 3.35 x 10^5 J. That's the easy part. To vaporize this water requires 2260 kJ of energy (2260 kJ/kg) (i.e. 2.26 MJ) Result: ~2.6 MJ. For every square centimeter of surface. And double that, because you wanted ~20m. More than 5 MJ/cm^2 That energy must be released when you go back to a liquid. This has an effect on temperature, to be sure. 2 bars of water is going to make for pretty difficult breathing. You've now tripled atmospheric pressure, assuming you can get this much vapor in the air (I don't think you can) and what you're breathing is mostly water vapor. Oxygen has dropped from ~20% to less than 7%

! Moderator Note Yes. Posting this evidence is required for further discussion. Otherwise, the response is “good for you” and thread closure, because we’re a science discussion site.

less divergence.

Blessed are the cheesemakers (really, any makers of dairy products)

All of these can probably be looked at with an historical lens. Humans from 5k years ago and isolated from other populations show, at most, minor physical differences. They were around different animal species, and so different diseases, so they would likely be susceptible to each others’ diseases. Just like “old world” and “new world” populations. Language would also have diverged.

Thank you. Never noticed that (each time we update the software, I am less interested in poking around to explore all the features). Looks like blocking followers is all or nothing.