Can water evaporate and freeze at same time?
When ice cubes melt, a solid and a liquid coexist, and when water evaporates, a liquid and a gas coexist. So, is there any state in which three states of water, solid, liquid, and gas reach thermodynamic equilibrium? The answer is triple point of water.
In thermodynamics, "triple point" refers to temperature and pressure at which three phases of matter (gas, liquid, and solid) can coexist. The triple point of water appears at 0.0076 °C (273.16 K) and 610.75 Pa, so under these conditions water will freeze upon evaporation.
How fast is spaceship?
We all know that spacecraft need a lot of speed to go into space, but whenever we hear statements like "It will take us 8 months to fly from Earth to Mars", it always seems to us that these spaceships are a bit too slow.
It's not really that spaceship is too slow, it's that universe is too big. The above animation is in stark contrast: far left is speed of a Boeing 747 aircraft, middle one is speed of an SR-71 Blackbird reconnaissance aircraft, and one on right is speed of New Horizons probe, which has already passed Pluto. The speed of spacecraft is already very high, but compared to great universe, it is still not worth mentioning.
How many ways are there to prove Pythagorean theorem?
Do you still remember how your teacher proved it to you when you were studying Pythagorean theorem? Draw a picture to draw it, or measure it straight with a ruler and calculate? I'm afraid there is nothing more intuitive than this device.
What happens when a black hole swallows a star?
When you're full, you tend to spit up, and when a black hole is "full" it does same. Scientists from Johns Hopkins University watched the spectacle of a "hiccup" black hole - a black hole with a mass of 1 million solar masses, having swallowed a star, releases a high-speed jet. Of course, since it is so far from Earth, it has little effect on us.
What if I don't wear glasses?
Myopic friends will more or less forget to put on their eyes. What should I do if I need to see very important things clearly at this time? In fact, you only need to make a small hole with your fingers, and picture will be much clearer when looking through small hole.
Why is that? Simply put, this small hole filters a lot of light, so that diffuse spot formed on retina by each luminous point of a distant object becomes smaller under condition of myopia, so that image becomes clear. However, disadvantage of this method is also obvious, that is, screen brightness is greatly reduced, but in emergency cases it is good.
What did you experience in womb?
Embryonic development is an incredibly complex process that scientists are just beginning to understand. But scientists have been able to map how your face is formed in womb. After watching this animation, and then looking at myself in mirror, I suddenly felt that I was quite handsome now~
How strong are solar flares?
A solar flare is one of most violent eruptions occurring in a localized region of solar atmosphere, when a large amount of energy is released in a short period of time. But how much energy is that? Each time it erupts, energy released is equivalent to simultaneous detonation of millions of million-ton atomic bombs. What is even more frightening is that such outbreaks happen all time.
What did cats do before they landed?
I believe many people have heard rumors that cats can't die from falling. Many foreign masters have made videos and made animations to study what happens when cats fall from a height. Many scientists have also published many academic studies on subject. this paper. However, there is still a lot of controversy on this issue, and due to “survivor bias”, a large number of fallen or even dead cats have not come to attention of people, so friends who have cats at home, please be understanding. take care of your owner. Don't use their lives as experiments~
Was it safer to hide in water during explosion?
The answer is that it's safer on ground, and farther you run, safer you are. The shock wave generated by an explosion attenuates with distance, and attenuation rate in air is much faster than in water. If grenade exploded in water, combined with enormous pressure of water, you will most likely look like a balloon in picture in the water.
What is trajectory of a spinning ball in air?
If you throw a basketball vertically, if you add rotation, its trajectory will not be a simple straight line. This is because rotation of ball sets surrounding air in motion, which causes speed of surrounding air to be different, which leads to a pressure difference and thus a change in flight path of the ball. This effect is widely used in various ball games such as football and table tennis.
July 26, 2023
July 26, 2023
July 26, 2023