# Tag Info

9

I can only give you a hand-waving explanation, but the fastest way to empty a bottle I have empirically found is to pour it upside down but rotate the bottle. The main problem is that the empty space above the water needs to be filled again with air which can not get through. If you rotate the bottle correctly, an air corridor inside the bottleneck opens and ...

5

10th grade is 15/16 years old right? Even if i'm more for a theoretical approach I think that age should be the age of experiments. He clearly doesn't have the mathematical background to do "real" theoretical physics. They just probably try to shove formulas into his head without explanations. I advice you to keep going with these kind of experiments, maybe ...

4

Option 3: Squeezing the bottle. Of course it depends how much pressure you are able to do, the strongest you are the fastest, and if you compress the bottle in an industrial press, the water will leave in a split second without breaking the bottle (well, it gets deformed, but that was an option).

4

For plastic water bottles of the market, Msha gave a video link ,in a deleted, unfortunately, answer because it just gave the link.For this case, plastic bottles, it should be the answer chosen. Crush the bottle fast, beginning from the bottom. The same will be true for any elastic type bottle. It is only glass bottles that have an unsqueezable limit. I ...

3

Tell him how to build an atomic bomb. Kids loves it. In principle: Start with a shocking and dangerous idea. Show him an exciting experiment and explain this. Make him do something what requires new knowledge. For example: Tell him about space exploration, that he can do it by himself, build a model rocket with him, Teach him the Newtonian dynamics ...

3

"Normal" in the context of oscillators simply means "periodic" – periodic solutions and the frequencies and other aspects associated with them. It's like in "he breathes normally" – the breathing seems to be periodic. "Quasinormal ones" are those whose time dependence is $\exp(-\Gamma t) \sin (\omega t)$, i.e. they have some exponential decrease aside from ...

3

The infinities of set theory aren't the same kind of infinities addressed with regulatisation or renormalisation. For example, if $\kappa$ is cardinal (be it finite or transfinite, which for some reason is the name used rather than infinite) then $2^\kappa>\kappa>0$, but the "infinities" we regularise or renomalise are $\pm\infty$, satisfying $2^{\... 3 There is something famously called "Feynman's famous formula", which comes up in QFT calculations, which I imagine must be the second FFF referred to in Welton's account. It reads: $$\frac1{a_1 a_2 \ldots a_n} = \int_{x \in \Delta^{n-1}} \frac1{(\sum_{i=1}^n a_i x_i)^n} d\sigma$$ where$\Delta^{n-1}$denotes the simplex$\{x = (x_1, \ldots, x_n) \in \...

2

You spin the bottle so that the water comes out like a tornado. This lets the air come in faster through a tube of space in the middle. The air pushes up forcing the water out leaving a space in the middle for air to come in. The rate of water flow is exponential. This is because the water lessens letting air come in faster, pushing the water out faster with ...

2

The question is: what is the optimal way to pour the water so that it [the bottle] completely empties fastest? I conclude the aim is to have the empty bottle, not the water in another container. Solution: Create a centrifuge-like setup, bottle opening to the outside. The setup will generate artificial gravity for the water in non-inertial frame of reference ...

2

Cut the bottle base and squeeze the bottle The air pressure has a major role to play in this situation. If you keep the bottle vertical, there wouldn't be any room for the air to move in as the water falls through which is the reason why you see turbulence and interruptions. There are various ways to tackle the issue. The best method would be to punch a ...

2

What I have observed is that if we turn the filled bottle (open) upside down and plug in a straw then the water starts to flow out faster. This happens because by plugging in a straw we make a way for air to come inside the bottle and fill empty space. Another observation that I've made is that when water is flowing out of a bottle (upside down) just shake ...

2

Hold the bottle upside down, your hand grasping it near the base. Extend your arm downwards. Make a circular, conical-shaped motion with your hand. Keep it up until you have a nice vortex going. Spinning too fast is counter productive; centrifugal force keeps too much water hugging the sides. You need a speed just a bit more than what's necessary to ...

2

language more general than math Sure, some of us call it English. I can teach and understand many lessons from physics without diving into the math. What's hard to do is discover or prove physics without math. "A body at rest tends to stay at rest. A body in motion tends to stay in motion." I can throw tons of math at that but the idea can be ...

1

There were two achievements of early humans and early civilization that led to us being able to state and understand the environment we lived in. One was writing, and one was math. Math started with counting, then adding, i.e. counting and arithmetic. Counting was invented very very early in the homo family by many different groups. Then arithmetic and math ...

1

I am telling this from my practical experience. In my home we have very poor water supply so we purchase 15 ltr water dispenser for drinking water. The guy needs to take the bottle back. So he shakes the bottle such that water make a kind of whirlpool while still keeping it straight and then quickly turns it upside down at an angle. The water flows quickly ...

1

It is generally a good idea to keep units out of your expressions for as long as possible. If you do that you are unlikely to run into trouble. Still, if you do have issues, you can just come up with you own typographic conventions if the notes are just for yourself. For instance, you could always keep your units to the far right and put curly backets or ...

1

Some care is needed when talking about quantum fields because they are a mathematical formalism for describing the properties of particles, and it is unclear to what extent a quantum field can be regarded as a physical object. Many of us are guilty of sloppy terminology such as the energy of a quantum field or transfer of energy betweebn quantum fields. ...

1

I think "normal" means also "proper to the system", i.e., existing after the system ceased to experience an external force.

1

I'll answer more in a clinical perspective. I don't know about extreme situations when the spins of your organism's atoms are rearranged in a lethal way, but as far as MRI magnets go, the first concern when using MRI equipment is the possible induction of electric currents inside the human body. These concerns are more prevalent for investigation MRI ...

1

Planck's work was not in resolving the ultraviolet catastrophe, it was in alignment with Wien's law (a thermodynamic approach). Douglas Stone goes into this issue quite in depth in his book on the history of quantum mechanics. Planck's role is seminal but also overstated (and he disagreed vehemently with Einstein's arguments in his 1905 and 1906 papers on ...

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