Want to ask something?
Send us an e-mail with the subject “Physics mysteries” to the address:
We can't wait to tackle your interesting questions!
Is the same person’s weight different at the equator and at the North Pole?
I don’t want to be a quibbler but with this question, it is clear that it is good to use the right terms for what we want to find out. Because I could easily answer yes or no, and in both cases I would be right ...
How are high tide and low tide created and why are they needed or important on the Earth?
The high tide and associated low tide are caused by the gravitational force acted by the Earth and the Moon on each other. Thanks to this force, the Moon orbits around us and does not fly away. This gravitational effect is also responsible for the fact that the Moon does not rotate on its axis, so that it always faces us on the same side ...
How do “assemblies” which seem to never stop work (swing with balls knocking against each other, spiral water “overflow”, …)?
The mentioned “physics toys” represent an experimental verification of one of the basic laws of physics (and nature) — the law of conservation of energy. Energy is actually stored work and we can store this work in various forms of energy (chemical, electrical, magnetic, mechanical, …). And these toys just transfer individual forms of energy into each other ...
What is the speed of thought? At what speed does the brain give the command to the big toe? How long does it take for the big toe to react?
I’m not a doctor but I’ll try to answer to the best of my knowledge and applications of physical phenomena. I will convert the term thought to the processing of information which is certainly a thought. Our body is (in my opinion) an evolution-improved machine with certain limits. These limits are mainly determined by our surroundings ...
Why is it better to ride a bike on the road with bigger wheels than with smaller ones?
Different drag forces act against the movement of bodies, this situation is described as rolling drag. The size of the rolling drag depends on several quantities — the force that pushes the wheel on in our case, the riding surface, the radius of the wheel and the arm of the rolling drag. All these quantities describe how the wheel and the surface deform when interacting with each other ...
How much water evaporates in 1 hour from 1 m² of water at a temperature of 30 °C?
Unfortunately, there is no simple answer to such a simple question. The rate of evaporation of any substance depends on many factors and only a few are listed. Specifically, the rate of evaporation depends on the material (which in this case is water), temperature (entered), area (also entered), pressure and vapour suction ...
Why can’t metal utensils be used in the microwave?
A microwave oven uses electromagnetic waves of a specific frequency for heating — 2.45 GHz. This frequency is not chosen randomly, it is the resonance frequency of water molecules. Resonance is an action in which we supply the oscillator (a body that oscillates) with such a frequency that its oscillation will continue to increase ...
Why and how does a rainbow form?
The formation of a rainbow is one of the proofs that light is an (electromagnetic) wave. When the wave encounters an obstacle, it can bounce off or pass through the obstacle. In the case of passage into an obstacle (and exit from it), the direction of propagation of this wave changes. In physics, we call this phenomenon refraction ...
What phenomenon explains that I have much more power with a pulley and I can pull a heavier object than when I lift it normally?
Although it may seem that a pulley (or an inclined plane or a lever) are special machines, using some strange aspect of physics, the opposite is true — these machines (we call them collectively simple machines) prove that everything works as it should and confirms the most basic principles of physics ...
What is the effect of mobile phone “radiation” on the brain?
The electromagnetic waves we use to make wireless calls are integral to our surroundings — and I’m not just talking about visible light. Electromagnetic waves of other frequencies, which we are unable to detect with our eyes, are coming at us from the entire Universe, most intensely from the Sun ...
How is it possible to compose any colour from RGB (red, green and blue)?
Our eye has 2 types of light-sensitive cells — retinal rods and cones. While rods respond to less intense light but not to colours, cones are less sensitive to light intensity but respond to colours. That’s why we see the outlines of things when it is gloomy but not their colours. So, we have to focus on the cones when it comes to colour perception ...
Will a heavier body achieve a higher free-fall velocity than a lighter one (of the same size)?
I like questions that I can always get right (or always wrong but I’m an optimist).The correct answer to such a question is yes and no. If I wanted to have only one correct answer, I would have to add to the question where the body falls ...
How is it that in a car accident, the speed of the cars do not add up and what is the resulting crash speed?
We probably intuitively know that there will be a difference when two small passenger cars collide and when a passenger car collides with a truck. It is obvious that the result of the collision is somehow related not only to the speed but also to the mass of both bodies. Therefore, we must include both the speed of both bodies and their mass in similar situations ...
Why do the days get shorter and longer?
The very alternation of day and night is caused by the rotation of the Earth around its axis. But that’s not the only movement the Earth makes, it also orbits the Sun. Orbiting around the Sun alone would not affect the length of the day, but the Earth’s axis is tilted (about 23°) relative to the Sun ...
How do I know that I managed to achieve fusion at home in the garage?
If I have a brilliant idea and build a device in my garage that could achieve fusion, how will I know I’ve really succeeded?
It depends on what kind of fusion reaction you are trying to achieve in your garage device. If deuterium-tritium fusion is your goal, get a quality neutron detector and a long cable to run from the detector in the garage to your computer. Deuterium-tritium fusion generates very strong neutron fluxes. One successful fusion of deuterium with tritium produces one neutron ...
Is there cold fusion?
All the fusion reactions we know need extremely high temperatures to take place, which is why they are so difficult to achieve on the Earth ...
What the particles need for successful fusion is not so much temperature but speed. Only when they rush towards each other with sufficient speed can they overcome the electrostatic repulsive forces and get close enough for the nuclei of the atoms to fuse. But to have high speeds means to have high temperatures in the world of particles ...
Will we run out of water because of fusion power plants?
The fuel for a fusion power plant is hydrogen, which can be obtained from water. If we met all of civilization’s energy needs only from fusion power plants in the future, wouldn’t we ...
I don’t think we have to worry about that. It is true that the deuterium required for thermonuclear fusion is obtained from seawater, but its consumption is very low compared to the volume of all the world’s oceans. It is estimated that a 1,000 MW fusion power plant could consume around 250 kilograms of deuterium per year. That is less than a kilogram of deuterium per day ...
How long does it take for a new star to ignite thermonuclear reactions?
At the beginning of every star, there is only a cloud of hydrogen gas, which begins to roll up and shrink due to gravity until suddenly, fusion ignites in it and the hydrogen cloud becomes a real star ...
From a cosmic point of view, it happens quite quickly, only a few tens of millions of years are enough. A star begins its life as a large ball of hydrogen that has condensed from a hydrogen cloud. In order for fusion reactions to occur, the hydrogen sphere must shrink enough to increase the pressure in its centre sufficiently ...
The NIF announced that they had finally achieved fusion. Does this mean we will soon have a fusion power plant?
In December 2022, the National Ignition Facility, which is experimenting with laser-driven fusion, announced that they had finally achieved “ignition” and that it was a major breakthrough ...
The success of the National Ignition Facility in an experiment on December 5, 2022, which released 3.15 MJ of energy in a fusion reaction using only 2.05 MJ of energy for the lasers required to ignite this reaction, is undoubtedly huge and a significant milestone in thermonuclear fusion research ...
How big a bucket of water would you need to put out the Sun?
You can put out a campfire with a few buckets of water or put out a forest fire with a small lake dropped from helicopters and airplanes ...
No bucket of water will be big enough to extinguish the Sun. On the contrary, the more water you pour on the Sun, the more it will burn. The fire we normally encounter on the Earth, whether it is a campfire or a candle flame, is based on a chemical reaction ...
