John Cuthber

I didn't look at the link- this is a slow computer + it would take too long. The equation PE= mgh is still wrong (A I explained earlier) You won't get the right answer by using the wrong equation.

There are plenty of labs where the staff wear gloves so that the samples don't get damaged by the people. If you ate your lunch off the bench your lunch would be fine- but someone would have to spend a long time cleaning the bench afterwards.

You do not gain 100 J of gravitational potential energy. How many times do I have to tell you this? Is it that you don't understand, or are you trolling?

Thorough what mechanism does moving figures around on a squared board control the sort of situation which we expect our diplomats to deal with? For example the testing of a nuclear weapon by North Korea is giving our diplomats something to think about. Why would chess not be a waste of their time?

A mosquito was heard to complain, that a chemist had poisoned his brain The cause of his sorrow, was para dichloro diphenyl trichloroethane. (Not original- I wish it was)

I rather doubt that it's possible- until you notice the broken bones. What's the problem with hospital? What's the problem with eating a diet that contains Vitamin D What's the problem with getting sunlight? Don't you have better things to worry about?

Really? I would have expected you to go with Proverbs 6:16-19 16 These six things doth the Lord hate: yea, seven are an abomination unto him: 17 A proud look, a lying tongue, and hands that shed innocent blood, 18 An heart that deviseth wicked imaginations, feet that be swift in running to mischief, 19 A false witness that speaketh lies, and he that soweth discord among brethren.

Or it's exactly the same as everyone else- and he's lying or mistaken. So why do you think the incredibly unlikely thing is true, rather than the obvious thing? What evidence do you have?

Building a nuclear reactor in the US at the moment is probably almost impossible politically. This "Should not they rethink their business model, and start producing it near North America.. ? " makes no sense because- unless there's a volcano going off, Europe is "near North America "- it's just a few hours on a plane. Meanwhile, back at the topic... The bulk of radioisotope work is done with radioactive tracers. The radiation- even in the test animal used in the experiment- has to be small enough not to affect the animal's health because that would invalidate the research. So these radioactive things are not generally very radioactive (there are exceptions but...) They try to avoid spilling them. There are laws (and associated lawyers) related to cleaning up radiation workplaces + restoring them to normal use.

Nonsense. How can you come up with that as a reply to a post that calculates the gravitational potential energy of something as 900 Joules? Did you actually read what I posted? i showed you how to calculate the potential emery of a body that is immersed in water. Why don't you do that calculation with the ball you are "experimenting" on? Then you will realise the mgh isn't the right answer.

Can we start by confirming the obvious- the circumstances where the beam bends upwards are (as my mathematical modelling friends describe it) "unphysical"? If I put a slab of glass on a hot plate and cool the too of it so I get a temperature gradient through the glass it will bend a ray of light that enters the glass horizontally and traverses it. It will bend towards the "cold" side of the glass- so that's upwards if the bottom of the glass is hotter. The same would, in principle, be true for a body of air that was hot near the ground, and cool further up. You could set that experiment up in zero gravity and check it. However if you heat the "slab" of air from underneath- for example- but a warm lake surface- you set the air in motion. You can't get a stable system with the warm air under the cold air. So you can't get a stable system where the ray bends downward. Never mind that this effect is small- the problem is that someone is pretending that it goes in the opposite direction.

It's trivial to debunk his experiment: it gives a result that implies the Earth is flat. we know that the Earth isn't flat* so there is something wrong with his experiment. * Anyone with a map of the world and a set of international flight timetables can prove this. However the interesting bit is to work out where he has got it wrong. So far,, he's ignoring gravity (which makes warm gases rise)- which is interesting, even if it's only a small effect..

Well, if it is 1 Kg of polystyrene foam (let's say it's density is a tenth that of water) and it's 10M from the surface, but in a water tank 20 metres deep then the conventional gravitational potential energy is negative- because it you let go of it, it will "fall" upwards. If we say that local gravitational acceleration is 10 m/s/s then the answer to your question can be calculated thus The volume displaced by the polystyrene is 10 litres. And, from Archimedes' principle, we know that it experiences an upthrust equal to the weight of the water it displaces so that's 100 newtons. Set against that is the weight of the block- that's 10 Newtons. So the net force acting on it is 90 Newtons (upwards). If you let go of it the block will rise by 10 metres to the surface of the tank. So the potential energy of the block is 900 Joules Now do you see why mgh has sod all to do with the calculation?

No it is not. Stop ignoring reality. This PE = mgh is wrong. It's small- but you need to multiply it by the surface area of the ocean- which is huge- to get the change you are looking at.

I tried to help. I tried to explain that you need to use the right equation rather than plugging numbers into the wrong one. I tried to get you to calculate how much energy you could get out of the system and I got drivel. So, why not do what i suggested? Calculate the buoyancy force on the ball, multiply it by the distance it can rise and find out just how wrong this PE = mgh is.

If you copy the sketch I did into a CAD package it will measure the lengths of the lines for you- but it will not tell you if they are a minimum. If you draft the equations for the total length as a function of the angle (90 degrees in my sketch, 120 in Sensei's) and then differentiate it wrt that angle you will find the minimum length for that layout- So maths clearly helps. but it's not the best layout.

How? If the air nearer the ground was warmer it would rise rather than sit there covered by cold air. The same is true for humid air which is less dense than dry air. If there were strong thermal currents when you made the measurements, that's another complication. Were there air temperature measurements at different heights?

This expression =ℎ ​is incomplete- as Swansont said. Imagine that you want to recover the energy from the ball as it floats to the surface by tying a string to it and passing that through a pulley at the bottom of the tank As the ball rises it pulls the string. You can use that to do work- for example- to lift a weight outside teh tank (you'd need a couple more pulleys). How much weight can it lift? Through what distance does it lift the weight? How much work is actually done?

As far as I can tell from a brief skim, nobody in this thread has mentioned the variation of refractive index with height. That make light bend down slightly as it goes through the air and throws the calculation out slightly. https://en.wikipedia.org/wiki/Bedford_Level_experiment#Refraction It seems you are in danger of repeating a 19th century mistake.

And that motor requires energy. That's why the conservation laws are intact.

Did you read the bit about a vacuum? The first ref. I found says the melting point of BiSb is 475C which is a bit high for glassware to stand.

Nobody asked you if it was well known did they? So, why did you post that, rather than actually answering the question? Do you mean this sort of thing? http://phl.upr.edu/library/notes/standardmass-radiusrelationforexoplanets If so, perhaps you might like to get the numbers right; it's rather less than the mass of Jupiter to rather more than 60 times that.

No. Where we differ is that I think evidence is important- because, without it, you might as well be talking unicorn dung.

What do you consider the word "proactive" to mean?

Proof? No, but I used paint which is free and lets you do it really badly.