Physics mysteries

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Can anything be faster than light?

Jaroslav Kores, Ph.D.

It can but it won’t do us any good. I will not deal with hypothetical particles (tachyons), which in my opinion are more of a mathematical game resulting from the Theory of Relativity. It follows from the Theory of Relativity that when speed increases, the mass of the body also increases. The faster the object moves, the greater is its mass ...
(Source: stock.adobe.com)

How long can a wind turbine propeller be so that it would not break?

Edita Bromova

More and more wind farms are being built around the world and they are getting bigger and bigger. Is there a limit to how big they can be? How long can a wind turbine propeller blade be so that it wou ...
The length of the wind turbine’s propeller blades has already exceeded one hundred metres. In 2022, the record was held by a 123 metre long blade from the Chinese firm Lianyungang Zhongfu Lianzhong Composites Group Co., Ltd. (LZ Blades). Even longer rotors can be expected to follow ...
(Source: stock.adobe.com)

Could nuclear fuel be made from coal or seawater?

Edita Bromova

Uranium is found elsewhere in the world other than in uranium ore. It is said to be contained in coal or sea water and there is quite a lot of it there ...
Uranium is a heavy element that was created by sequential neutron captures in the cores of massive stars, which then ended their lives as a supernova and scattered most of the elements from their core into the wide space environment, including uranium. Planets eventually formed from this interstellar dust ...
(Source: stock.adobe.com)

Can a photovoltaic panel produce electricity at night?

Edita Bromova

A photovoltaic panel generates electricity from the incident light, so in theory it could also generate electricity at night from the light of the stars and the moon. Or from the glow of street lamps ...
A photovoltaic cell produces electricity after the impact of any photon with a suitable wavelength and does not care if it came directly from the sun, bounced off a wall or the moon or flew out of a light bulb. In all cases, the photon induces a photoelectric effect, which leads to a voltage at the output from the photovoltaic cell ...
(Source: stock.adobe.com)

What lives in the area of a nuclear power plant?

Edita Bromova

I wonder if there are any animals living in the area of a nuclear power plant and what do they look like ...
The site of a nuclear power plant usually occupies an area of approximately three square kilometres and includes, from the animal’s point of view, a number of attractive biotopes. There are grassy areas for insects and small animals, bushes, roofs, ledges and pipes providing safe shelters and nesting opportunities or open pools under cooling towers for aquatic creatures ...

Why does atmospheric pressure change and how does it affect humans?

Jaroslav Kores, Ph.D.

Atmospheric pressure varies mainly with weather and also with altitude. Because atmospheric pressure is the pressure caused by the weight of the air column, the higher we are, the smaller the height of the air above us and thus the weight of the air column is smaller and therefore the atmospheric pressure too ...
(Source: stock.adobe.com)

What is a photovoltaic panel doing with the sun shining on it when no one is drawing electricity from it?

Edita Bromova

The photoelectric phenomenon inside the photovoltaic panel takes place every time the sun’s rays fall on it ...
A photovoltaic cell is a thin wafer of silicon modified to function as a semiconductor photodiode. When a photon hits its surface, it transfers its energy to one of the electrons, which is released from its electron shell. When enough electrons accumulate, a voltage is generated at the output of the photovoltaic cell ...

How is gravity produced on a spaceship?

Jaroslav Kores, Ph.D.

Gravity is a property of all material bodies and cannot be directly “produced”. Since the magnitude of the gravitational force depends on the mass and distance of the bodies acting on each other, we can make a smaller model of the Earth with the same gravitational effects on its surface ...

Can water somehow be lost to space, i.e. decrease on the Earth?

Jaroslav Kores, Ph.D.

It certainly can, and in my opinion, it happens to a very limited extent. If we want anything to leave the Earth’s gravitational field, we have to give it the so-called 2nd escape velocity (or Ve). Everything we throw/fly slower will come back or will orbit the Earth in an ellipse. The value of this speed is (at the Earth’s surface) 11.2 km/s ...

Why doesn’t the Moon fall to the Earth?

Jaroslav Kores, Ph.D.

The fact that the Moon orbits the Earth, does not fall on it and does not fly away, and in fact, the fact that it has become our companion, is due to a suitable combination of the speed of the Moon and its distance. According to Newton’s first law, bodies on which no force acts move in uniform rectilinear motion. If a force acts on a body, the body will move with acceleration ...
(Source: stock.adobe.com)

Can wind turbine rotor tips spin at supersonic speed?

Edita Bromova

The larger the wind power plant, the faster the ends of its propellers are spinning. Could it be that if the wind farm is very large and the wind is strong, the tips of its propellers will start to sp ...
Small wind turbines can reach 30 to 60 revolutions per minute, but larger ones spin more slowly at a rate of perhaps only ten revolutions per minute. What may look like slow motion from a distance is actually quite fast when you focus on the tips of the propeller blades ...
(Source: stock.adobe.com)

Could early humans have had a nuclear reactor?

Edita Bromova

It is said that once upon a time there was a natural reactor in the rocks somewhere. If this is the case, could the first early humans have warmed themselves with it? Couldn’t they have bak ...
A natural reactor really existed. It was “operated” in the Oklo locality in the West African state of Gabon. The uranium ore deposits there at that time contained around three percent of the isotope 235U, which is a concentration sufficient for current nuclear reactors ...
(Source: stock.adobe.com)

What does a heat pump need electricity for?

Edita Bromova

A heat pump is said to be a miraculous machine that will heat my home from heat collected somewhere outside. But now I found out that it needs electricity to operate ...
A heat pump is actually a bit like a refrigerator. While a fridge takes heat from its interior and heats the room in which it stands, a heat pump takes heat from the external heat reservoir to heat the interior of the house. A suitable reservoir can be the surrounding air, the ground on which the house stands or a water tank ...
(Source: stock.adobe.com)

How small can a nuclear reactor be?

Edita Bromova

Nuclear reactors in nuclear power plants are quite large. But how much fissionable uranium do we need, so that a controlled reaction can take place in it and produce heat? Can we build a nuclear react ...
The smallest amount of fissile material in which a fission chain reaction can take place is called the critical amount. Most of the neutrons produced in it during fission continue to participate in fission. This allows the reaction to run continuously. The critical amount depends on the type of fissile material, its concentration and the shape in which it is arranged ...
(Source: stock.adobe.com)

Can radioactivity be seen?

Edita Bromova

It is said that radioactivity cannot be seen, heard or felt. But isn’t there the possibility that we could see it under certain circumstances? Aren’t there any animals, whose senses would ...
Ionizing radiation is all around us. It arises from the decay of atoms in our surroundings and in our own bodies or it comes to us from space as cosmic radiation. We call materials containing unstable isotopes radioactive, but since everything around us is slightly radioactive, we have not developed senses to detect radioactivity ...

Why do I tan more in winter than in summer?

Jaroslav Kores, Ph.D.

To be honest, I haven’t experienced this but it’s probably because I don’t sunbathe much. I don’t know if the winter tan is also related to the skiing/mountain activities. If this is indeed the case, I think it has two causes ...

Why can’t you make a fire using a magnifying glass and some “special” flashlight or moonlight?

Jaroslav Kores, Ph.D.

It would certainly be possible but we would need either a better flashlight or a bigger magnifying glass. About 1,000 W/m2 of energy reaches the Earth from the Sun. If the Moon reflects roughly 20% of the falling sunlight, we would need a 5x better magnifier (i.e. a magnifier with a 5x larger surface, i.e. a 2.3x larger radius) ...

According to what pattern do sunrises, sunsets, moonrises and moonsets change?

Jaroslav Kores, Ph.D.

The movements of bodies in the central gravitational field are described by Kepler’s laws, of which only law 3 has the form of a formula. Isaac Newton used Kepler’s laws to formulate (his) law of gravity ...

Can someone break a glass or any object with their voice (sound made)?

Jaroslav Kores, Ph.D.

Everything can be broken, the only question is how difficult it will be. It will be simple in theory with a glass but I personally wouldn’t trust the implementation, especially due to the absence of a musical ear? When we tap the glass, we can hear a sound. The pitch (frequency) of this sound depends on the material and shape of the glass ...

Why can engine performance be determined by “horsepower”? Is it some kind of conversion to real horses? What kind?

Jaroslav Kores, Ph.D.

Horse power was introduced by James Watt to be able to approximate the power of the steam engine. Simply put, by determining the horsepower of a horse and comparing it to a steam engine, he could say: “My steam engine will replace 10 horses”. This way it was easy for everyone to imagine and was certainly well thought out in terms of marketing ...
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