1Can water boil and freeze at same time
When ice cubes melt, a solid and a liquid coexist, and when water boils, a liquid and a gas coexist. So, is there a state in which three states coexist: water, solid, liquid and gas? The answer is: triple point of water.
In thermodynamics, a "triple point" is value of temperature and pressure at which three phases (gas, liquid, and solid) of a substance can coexist. The triple point of water occurs at a temperature of 0.0076 °C (273.16 K) and a pressure of 610.75 Pa, therefore, under these conditions, water will freeze when boiled.
2How 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 animation above is in sharp contrast: far left is speed of Boeing 747, middle one is speed of SR-71 Blackbird, and right one is narrower than flyby speed of New Horizons probe strong> over Pluto. The speed of spacecraft is already very high, but compared to great universe, it is still not worth mentioning.
3How many ways 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.
4What 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 at Johns Hopkins University have observed spectacle of a black hole hiccup: a star with a mass one million times that of sun shoots out a high-speed jet after it has swallowed star. Of course, since it is so far from Earth, it has little effect on us.
5What to do without 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 in myopic conditions, diffuse spot formed by each luminous dot of retina on a distant object becomes smaller< /strong>, thus make image clear. However, disadvantage of this method is also obvious, that is, screen brightness is greatly reduced, but in emergency cases it is good.
6What 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 looking at myself in mirror, I suddenly felt that I'm pretty handsome now~
7How strong are solar flares
A solar flare is one of largest eruptions that occur in a local area of the Sun's atmosphere and release a large amount of energy in a short amount of time. But how much energy is that? Each time it erupts, energy released is equivalent to millions of million-ton atomic bombs exploding at same time. What is even more frightening is that such outbreaks happen all time.
8What cats did before landing
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 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 take care of them Good host, don't experiment with their life~
9Isn't it safer to hide in water when it explodes?
Answer: safer on ground and safer how far you can run. 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 water.
10What 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, causing speed of surrounding air to vary, resulting in a pressure difference and thus changing trajectory of ball. This effect is widely used in various ball games such as football and table tennis.
September 03, 2023