The school experiment of hanging two balloons, one filled with air, other empty, on a ruler, show that air has weight.
A person has weight. It's shown on a weighing machine. A pencil has weight. It's shown on a sensitive weighing machine.
None of these machines show the weight of air even under an open sky. Why?
I researched online. Found the following:
- Air column under an open sky when standing on the surface of the Earth is heavy enough to be shown even on the large weighing machine.
So, both of my weighing machines should show the weight of of the atmosphere.
- Air pressure inside the weighing machines balance the air pressure / weight outside.
That do not seems right. Air inside machine do not change by taking it out under open sky. Its pressure obviously cannot change thus. How do it balance both the air weight in room and under open sky?
Also, if it do where the extra energy came from?
Also, air molecules in the weighing machines have to vibrate more to have more pressure, right? How else would the increase in pressure manifest / happen? More vibration means more temperature because thats what temperature is. We observe no such thing.
I am aware of action reaction phenomena. If I push wall, wall push me back with equal and opposite force. However, this cannot solve this because then the weighing machines would not show weight of me and pencil.
- An answer to this question here says pressure is equalized on all sides.
I do not see how this can help even if true my weighing problem. Even if I am squeezing my weighing machines at all sides the upside (where scale is) would show the weight. The body of the weighing machine made of steel and thick enough can handle that pressure at sides.
The pressure is not equal at all sides. (i) There is no pressure from ground direction (upwards). (ii) Sides of my yard where I stand under open sky are much shorter than air length above me (100 km vs 20 ft).
I am careful in changing only one variable. The location of the machines. My friend did the opposite experiment with me at the same time and about 2 feet from me. He got himself weighted under open sky and in the room. His weight comes equal at both places. Why?
I can see that it is something with confining. Air in a balloon is exerting less pressure upwards to counter its weight. May be due to equal sideways and upwards dimensions. The air-filled balloon is somewhat like a ball in my experiment, more air pressure is going sideways than upwards. I filled an oval-shaped balloon with air, hang it with my hand long side up. It quickly fall to side. So, less long dimension get more pressure. Length of atmosphere upwards is just 100 km, breadth is 40,000 km at least at one side wherever you are on earth and on both sides if you are at equator. So, this do seems like the reason why air show no weight on my weighing machine. The pressure of air upwards is more than its weight downwards. Is that it?
This does not explain why sun has fusion though. Where do the pressure comes from if gravity does not work that way? You see if air on earth given column of just 100 km can cancel its own weight plasma in sun which is much more vibrant and have much larger dimension to move into would easily cancel its own weight. Then there would not be enough pressure due to gravity (weight) to reach temperature of millions of degrees of centigrade to start fusion.
Why do observation show air is weightless?