Science Notes/Written in the Past (7) 썸네일형 리스트형 Helmholtz Resonator - how blowing bottles creates sound(페트병 불기의 원리) When you blow the top of a bottle, it usually makes a wind instrument-like sound. The pitch seems to be higher when there's less water in the bottle. How is this sound made? The answer is: helmholtz resonance. When wind is blown to the top of the bottle's neck, it can be thought that air in the part of the bottle's neck resonates up and down. Since this is the only movement of air in the bottle(.. How red eyes are caused - the science behind it(눈 충혈이 일어나는 이유) Red eyes(bloodshot eyes) happen by various reasons - from allergies to even exposure to sunlight. A list of these causes are: allergies dry air/dust too much exposure to sunlight gas substance in the air (gasoline, etc) chemical substances smoke/flue gas All of these can be harmful to your eyes and cause inflammation. In order to prevent or stop inflamation, your body causes vasodilation of bloo.. Why doesn't the atmosphere vanish into space?(대기가 날아가버리지 않는 이유) The space is very close to a vacuum. It has nearly nothing that's not a part of a celestial object, like Earth. Imagine a vacuum cleaner, which works by sucking dust from the floor. That's right! Vacuums have a characteristic in common: sucking objects. But actually, a vacuum doesn't 'suck' objects. It is just an extreme case when the density of matter in and outside a container is different. So.. Why do you shiver when you're cold?(추울 때 왜 몸을 떨까?) When you are cold, you body just starts to shiver. What is the reason that our bodies do so? When your body's temperature starts to drop, the brain orders muscles all around your body to repeat contraction and relaxation. Contraction is when a muscle tightens, and relaxation is the opposite. When muscles contract and relax, they produce heat. The brain orders the body to shiver to get this heat... Diving Reflex - What is it?(잠수 반사) When you suddenly go into a pool of cold water, your breath becomes rapid. Same is when you are sprayed with cold water. This kind of reaction seems useless. But then, why does this happen? This phenomenon is called a 'diving reflex'. Every species in the class Mammalia(mammals) have this reflex, occuring stronger in sea mammals than those living on the land. This diving reflex leads to some eff.. Why does the moon look bigger near the horizon?(달에 대한 착시현상) In 2017, when I was on a trip with my family, I noticed that the moon looked way much bigger than it usually was. I wondered why and decided to research more about the phenomenon when I got home. There is no proven reason to why the moon looks bigger near the horizon. However, one thing is for sure: that it has something to do with our brain's functions. The current most widely accepted theory i.. The Standard Model(표준모형) Over time, scientists have tried to hack matter into smaller pieces, to find what the world is made out of. Empedokles(490~430 B.C.) first thought that everything in the world were combinations of 4 things: fire, water, air, and soil. That idea has been accepted for centuries, until Democritus thought of atoms, the most elementary matter that could not be broken. After that, people found out tha.. 이전 1 다음
