57

The domestic chicken's egg shell has about 7000 pores that allow the embryo to breathe. When an egg rots the yolk and surrounding materials decompose and they give off gasses which can pass through the shell. This allows mass to leave the interior of the egg resulting in less density for the volume of the egg making it more buoyant.


52

TL;DR: You have probably not been exposed to 100°C water in either phase and even if you had, you could not have reasonably felt its temperature on account of receiving a third-degree burn. Hot water and steam are both dangerous but fundamentally different, so comparing them is like gorilla vs. shark. I am not exactly sure what you are comparing here, but if ...


47

What we define as "hot" or "cold" is the transfer of energy -- how much (quantity) and how fast (rate of transfer) -- and how it raises our temperature. The more energy that is transferred from the object quickly, the hotter the object feels. First, steam is in a vaporized phase -- which is why it has more energy. At 100 Celsius, water ...


42

Your example is not an ideal one to illustrate the underlying principles, as the factors that prevent you from unfolding the paper involve many trillions of molecular interactions within the paper, which amount to a very complicated mechanism to visualise. Consider instead a simpler set-up with vastly fewer moving parts as follows... Imagine it is the start ...


38

These are probably Reflection Caustics. The video Taming light reflection to create images discusses engineered caustics (refractive rather than reflective in this case). See also this post from the EPFL Geometric Computing Laboratory: I don't think the explanations of refraction from density variations in air actually work in this case. Schlieren ...


31

It doesn't need to be rotten. When the egg is getting old, it evaporate water and looses mass while drying. Even if not rotten.


29

When you fold a piece of paper to create a sharp crease, you are permanently damaging the structure of the paper, and that damage (disconnection of bonding between adjacent cellulose fibers and breakage of fibers themselves) cannot be repaired by unfolding the sheet and flattening out the crease: it is irreversible. (This is easily demonstrated by observing ...


23

Without knowing all the details, it seems very likely to me that these are refraction shadows from hot and cold air mixing. The fact alone that it happens near an AC unit which gets cold on the inside and hot on the outside supports this. Here's what you can do to test whether this is true: Get a fan and direct it onto the outside part of the AC unit. If the ...


11

Well, I can think of the following reasons: First, it is much easier to exert considerable vertical force on the pizza cutter because the point of contact falls close to the hand, thus minimizing the torque on it (as compared to a long knife). This increases the efficacy of the pressure-based method of cutting (it requires considerably more pressure than the ...


10

It's caused by the same effects as cause a mirage: uneven atmospheric densities. In your case, the A/C housing is warm, either because it's running or because the sunlight has heated it. As a result, there is a column of heated air flowing upwards, mixing with cooler air, and generally going (mildly) turbulent. The different densities of the air lead to ...


9

Welcome to the physics SE! This is a really cool question to which I hope to add a really cool answer. I like Noah's answer because it includes an experiment. Here is a simpler experiment: Note the pattern with the AC running, then turn off the AC unit entirely, wait a few minutes for it to quiet down, and then see if the pattern disappears. If it does not ...


9

If you were to actually feel both liquid water at 100C, and true steam(not some Water vapor in air) at 100C, then the water will feel hotter. Note that the stuff that comes out of a kettle is not steam. Note that a sauna is not filled with steam. Because the water will inflict a first-degree burn in 0.25 seconds, causing pain. But the burn will take almost ...


8

First, let's cover how a pushup is done on the floor. Your hand applies a force onto the floor, and the floor applies an equal and opposite force on you, which you use to push yourself up. The important part is that you push on the floor. However, the floor, being very rigid and massive, does not deform or move. Next, let's consider a trampoline or a ...


7

Based on some heat transfer experience, these effects can be quantified fairly easily if we neglect convective heat transfer in the water and steam, and assume that the thermal properties of flesh are about the same as those of liquid water. In that case, if the liquid water at 100 C is suddenly brought into contact with flesh at 37 C, the interface ...


7

The first thing we need to realise is that we cannot that easily apply the typical formulation of entropy as the number of microstate realisations of a macrostate as the distinction between micro- and macrostate is less clear in paper. Like for every solid, the paper’s structure is fixed on some rather microscopic level: Unless you tear it, crease it, or ...


6

If you understand the structure of paper it is obvious that folding or tearing increase entropy Paper is made by breaking down wood (or for fancy paper, some fabric) into its constituent fibres and then reassembling those fibres in a very ordered way. The fibres are aligned in the plane of the thin layer as a suspension and then dried to preserve the order. ...


6

As the yolk decays, they emit hydrogen sulphide, which builds up inside the egg. Really rotten eggs can pop quite easily, which is something you need to be careful of when clearing out old nests. If left for long enough, a good few months, the yolk and the white will evaporate altogether, leaving just a shell and an awful lot of gas. They make a surprisingly ...


5

The air currents in the room due to the ceiling fan cause pressure variations on both sides of the curtain. If instantaneously the curtain is very close to the wall with a "film" of air in between at rest, then the fast moving air on the fan-facing side creates a lower-pressure region in that side. The relatively higher-pressure air on the other ...


4

There are I think only two ways to prevent your body from phone radiations. The first one is as @Yejus said creating a Faraday Cage. You can make a very cheap one with aluminium foil. The problem for this solution is that it will block electromagnetic fields emitted by your phone, but also the ones that it is supposed to receive, making your phone useless. ...


3

The methods in the link you give are good. In 'other tests' number 3, a torch is shone through the egg, but why does the boiled egg not allow as much light through as the liquid egg? Have you never cracked a raw egg? The uncooked white is not white, it is a colorless jelly. When you shine a light through, it is only the yolk that will stop diffusion. If it ...


3

The density changes for the rotten egg. Either the volume changes, i.e. gases expand the egg slightly or the mass changes - maybe the shell is slightly permeable to gas and the rotten egg expels some gas thus becoming less massive. Sorry not sure which.


3

When aluminum is plastically deformed as during the wrinkling process, the aluminum right in the wrinkles gets stronger than the undeformed aluminum. This process is called strain hardening and is most easily demonstrated with a piece of aluminum wire. If you bend the wire into an angle and then try to unbend it again, the bent zone resists unbending more ...


3

I would imagine that as the fan is creating downwards movement of air in the middle of the room, there must also exist an upward movement of air along the walls (and the window). This updraft would move the curtain in fairly unpredictable way, but probably starting as you described in Fig. 2, by pushing the bottom end of the curtain towards the wall/window. ...


3

why does lower gear generate less acceleration/speed of the car compared to higher gear? You are mixing up acceleration and speed. Acceleration and speed are different and behave differently in the lower and higher gears. Lower gears give higher acceleration and lower speed . Higher gears give lower acceleration and higher speed . To get an intuitive ...


3

You are writing that the force on the road minus the force on the leg is equal to mass times acceleration. This is common mistake and is not how Newton's law works. You can se this if you ask yourself what mass and whose acceleartion would you consider in the right hand side of the equation. The leg's or the road? The corrct way to use Newton's second law is ...


2

Paper is made out of cellulose fibers which are bound together by small amounts of glue under significant heat and pressure in the paper mill. Under a scanning electron microscope the surface of a sheet of paper looks like a haystack that has been smashed flat by great pressure. As long as the glue (called binder) retains its grip on the deformed cellulose ...


2

For something like a vane or cup anemometer that actually measures wind speed directly, I don't see why the anemometer would not indicate the same windspeed regardless of density with error due to friction (which would increase as air density or wind speed decreases). It would take longer to adjust to changes in wind speed if the air was less dense though. ...


2

First point: How hot or cold something feels doesn't purely depend on temperature. Temperature is just an (extensive) measure of the contained thermal energy amount. Rather, the important property is thermal conductivity for solids during conduction and the similar heat transfer coefficients for liquids and gases during convection. That is, the ability of ...


2

I would like to mention some things the other answers do not address: The way you create a flat, wrinkle-less, crease-less paper is to apply heat (and other processes), but bottom line, you need to add energy to the quantum mechanical system of molecules. By that, you do two things: you create covalent bonding between certain molecules in certain ways, and ...


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