字幕列表 影片播放 列印英文字幕 It's AumSum Time Can you guess the title of my next video? Hurry up. Write your guess in the comments section below. How do stars form? Stars are like huge balls of fire that emit a tremendous amount of heat and light. Stars don't form in a few seconds, minutes or hours. Star formation process is so slow that it can take millions of years. A star begins its life inside vast molecular clouds of dust and gas. These molecular clouds are also known as nebulae or dark nebulae. They mostly contain hydrogen and helium molecules along with some other particles. Now, let us hold on for a second and try to answer a question. In Latin, nebula means: Dust. Gas. Snow. Mist. And your time has begun. Start guessing. C'mon, C'mon, C'mon. Get that brain working and write your answer in the comments section. The correct answer is option number 4, that is, mist. Let's get back to our video. Normally, these molecular clouds are cold and stable. However, a nearby supernova explosion or galactic collision may send a shockwave or tremendous amount of energy through a molecular cloud. Now, in the molecular cloud. This energy causes a gravitational disturbance due to which it begins to collapse on itself under its own gravity, Causing hydrogen and helium to clump together. Thus, increasing the mass in the center of the cloud. This increase in mass, increases the gravitational pull. Thus attracting even more molecules and particles from the surrounding. As more and more molecules and particles collapse or fall into the center of the cloud, the center begins to heat up. This heated center or heated core is known as a protostar. Now, before going further, I'll ask you a question. What are shooting stars? Dead stars. Meteors. Migratory stars. Rogue stars. C'mon guys. Clock is ticking. Start typing your answers. The right answer is option number 2, that is, meteors. Now, let's continue with our video. A protostar continues to pull more molecules and gets hotter and hotter until the temperature. Pressure reach to such an extent that hydrogen nuclei begin to fuse with one another producing helium. Releasing heat, light and radiation. This process called nuclear fusion. When this happens. The inward force of gravity is exactly balanced by the outward force created by heat and radiation. These inward and outward forces maintain balance and thus, a star is born. Topic: Electric Charge. How does a plastic comb attract paper? What? You don't believe me? Ok. Let us try. Take a plastic comb and bring it close to some pieces of paper. Hey, Wait. Don't laugh. We need to do something first. Rub the comb on your dry hair and then bring the comb close to the pieces of paper. See, I was correct. The pieces of paper got attracted to the plastic comb. Do you think it is magic? No, the reason behind this is electric charge. Electric charge is the quantity of electricity held in an object. There are 2 types of electric charges, positive and negative. However, there are some objects where the positive and negative charges are equal to one another. In such cases, we say that the object is electrically neutral. So, was the plastic comb initially electrically neutral or electrically charged? Initially, the plastic comb was electrically neutral. That means it had equal number of positive and negative charges. Hence, it did not have the ability to exert a force and attract the pieces of paper. So, after rubbing the plastic comb on our dry hair, why was it able to attract the pieces of paper? I will tell you why. When we rubbed the plastic comb on our dry hair, it gained an electric charge. Once it got electrically charged, it got the ability to exert a force on the pieces of paper and attract them. This charge is called as static electricity. However, do you think, like a plastic comb, a metallic comb will also attract the pieces of paper? No, you are wrong. A metallic comb will not attract the pieces of paper like the plastic comb. Wondering why is that so? It is because plastic is not a good conductor of electricity. It does not allow the electric charges to flow through it onto the earth. As a result, the charges build in the plastic comb. Making it electrically charged and enabling it to attract the pieces of paper. However, metal is a good conductor of electricity. It does not let the charges build in it. It allows the electric charges to flow through it onto the earth. Thus, not allowing the metallic comb to get electrically charged. As a result, the metallic comb does not attract the pieces of paper.
B1 中級 美國腔 星星是如何形成的?| 星星是如何形成的? (How do Stars form? | #aumsum) 7 1 AumSum 發佈於 2021 年 01 月 14 日 更多分享 分享 收藏 回報 影片單字