Subtitles section Play video Print subtitles It's AumSum Time Which came first: Chicken or Egg? I, me and myself. You wish. There are numerous debates and theories on who came first. One popular theory is the Proto-Chicken Theory. What is that? During reproduction, two organisms pass on their DNA to the egg. Each time, tiny changes or mutations take place in the DNA. Over thousands of years, these changes create new species. Experts theorize that one such new species was the Proto-Chicken. Very similar to present day chicken. When the Proto-chicken laid an egg, mutations in the DNA created the First True Chicken. Now, which came first, depends on what we call the egg. If we say that the Proto-Chicken laid a Proto-egg, which created the first chicken. Then the answer is, Chicken came first. However, if we do not call the egg a Proto-egg, and instead, call it a chicken egg, then egg came first. Electric charge. How does a plastic comb attract paper? What? You do not believe me? Okay. Let us try. Take a plastic comb and bring it close to some pieces of paper. Hey wait. Do not 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. Heat transfer. Why are cloudy nights warmer than clear nights? Hey. Look at the weather outside. It is too cloudy. No. Do not go near that bonfire. It is going to be warm tonight. You do not want to listen to me, right? Alright. Go ahead. Look. I told you. At least now will you listen to me. During the day, our earth receives light from the sun and gets heated. Now, during a clear night, that is, when there are no clouds. This heat easily escapes through the atmosphere into space, resulting in cooling of the earth. Now, to understand what happens on a cloudy night, let us heat the earth once again. In this case, the clouds act like a blanket, preventing the heat from escaping into space. Since the heat remains in the atmosphere, cloudy nights are warmer than clear nights. Density. Why do firemen crawl in smoke filled rooms? Hey. Remember, the upper part of the room will be filled with smoke. So, crawl while you are going inside. I will not. My legs will become dirty. Why don't you listen? Look, you are not able to breathe properly as you have inhaled a lot of smoke. This happened because you did not care about the density of air. Well. I know all about cavity, but what's this new thing called density? Do not worry. I will explain. Density is the measure of mass present per unit volume. Lesser the density, lighter will be the object and greater the density, heavier will be the object. So in this case, what is lighter, the air or the smoke? Wait. Let me think. I guess the answer is smoke. Yes, you are absolutely correct. Smoke is lighter than air. As it is lighter, it rises up in the room and occupies the space at the top. Hey. Where are you going? It is not over yet. The air being heavier than smoke tends to remain below. Hence, if we crawl, we will get sufficient oxygen to breathe. We can safely come out of the room without being suffocated. Nerves. Why don't we feel pain when we cut our hair? Because if it would, then we would have got angry on our hair dressers. You are just impossible. Wait. I will explain it to you. Inside our body, there is a network of nerves. These nerves help us to sense our surroundings and feel pain, touch, etc. By sending messages to the brain. So, do the nerves of my hair not know how to send a message? No. Generally, the part of our hair above the skin is made up of dead cells. It does not have any nerves. Hence, when we cut our hair, due to the absence of nerves. Our brain does not receive any messages of pain. As a result, we don't feel any pain. Friction. Why is it difficult to pull a boat on the beach than on the sea? Hey. You will find it difficult to pull the boat on the beach. Pull it on the sea. There it will be quite easy. Indeed. Why not? Fine. Do not listen. I am so tired. At least now try to pull the boat on the sea. It is quite easy, right? Do you know why? This is because of friction. Friction is the force which opposes the motion of an object. It always acts in the direction opposite to the direction of motion. The amount of friction depends upon the texture of an object and the surface on which it is being moved. Rough textures or surfaces offer greater friction as compared to smooth textures or surfaces. Do you want to say that my brand new boat has a rough texture? No. Even though the texture of the boat is almost smooth. The small particles of sand present on beach form a rough surface. Hence, when we pull the boat on beach, the sand particles offer greater friction. Oppose the motion of the boat, thus making it difficult to move the boat on a beach. However, the sea being a liquid, forms a smooth surface. Hence, when we pull the boat on sea. It offers less friction, thus making it comparatively less difficult to pull the boat on sea. Forced vibrations. Why does a guitar have a hollow box? To keep clothes while traveling. Not at all. Wait, I will explain. Whenever we strike an object, it vibrates. Sometimes, these vibrations influence other objects to vibrate. The vibrations which take place under the influence of an external periodic force are called forced vibrations. So, whenever I see delicious food, my stomach starts to vibrate. Is this a type of forced vibration? Please concentrate. A guitar has a hollow box which holds quite a huge volume of air. Now, when we strike its string, it starts to vibrate. These vibrations influence the air in the hollow box, producing forced vibrations in them. Now we know that vibrations in air produce sound. Hence, as a huge volume of air is vibrating, the sound produced is louder. Pneumonia. What causes pneumonia? The letter P. No. Pneumonia is a lung infection caused by microorganisms. Which generally leads to difficulty in breathing. Normally, we inhale oxygen rich air which reaches our alveoli. Alveoli are surrounded by blood capillaries. Here, the oxygen through the walls of alveoli diffuses into our blood. However, sometimes we also inhale harmful microorganisms. Mostly, the cilia and mucus in our respiratory tract trap these microorganisms. Which are then expelled while coughing. But sometimes the microorganisms don't get trapped and reach the alveoli. There they start to multiply, causing lung infection, that is, pneumonia. Oh no. Now what to do? Now, to protect ourselves, the immune cells start attacking the microorganisms. Causing inflammation and accumulation of fluid in the alveoli. As a result. The inhaled oxygen cannot get easily diffused into blood, thus causing difficulty in breathing. What is earwax? It is a wax used to make candles. Gross. Not at all. Earwax is used to lubricate and protect our ear canal, middle ear and inner ear. But how does it form? Our ear canal consists of special glands. They produce an oily and waxy substance called cerumen. Cerumen moisturizes our ears. It traps dust and dead skin cells, keeping our ears clean. Besides this, cerumen also has antibacterial properties. When harmful microbes try to enter deeper into our ears, the cerumen traps and kills the microbes. These dead microbes, dust, oil and dead skin cells together form the earwax. Why do mosquitoes bite only some people? Because they are lazy. No. There are a number of reasons why some people are more prone to mosquito bites. One of them is body odor. Millions of bacteria which live on our skin produce various gases. These gases form our body odor. Some of these body odors attract the mosquitoes. So, this is the reason why mosquitoes prefer me. Besides this. A popular research found that. Mosquitoes tend to bite people with Type O blood nearly twice as often as those with Type A. Exercising can also entice mosquitoes. This is because when we exercise, we release more carbon dioxide, heat and sweat. Mosquitoes can detect this carbon dioxide and heat. They can also sense various substances in our sweat such as lactic acid. Thus making us more likely to get bitten. Hello Why does our voice sound different when recorded? Our inner ear detects sound vibrations, informing our brain about the voice or sound. Thus, helping us hear. But did you know that when we speak, we hear our own voice in two different ways. What? In two different ways. Indeed. The first way is through our outer ear. Our voice travels to the outer ear, creating vibrations in the eardrum. These vibrations eventually reach the inner ear. While the second way is through our flesh and skull bones. However, they are better at transmitting deeper, lower frequency sounds. As compared to shriller, higher frequency sounds. As a result, the combination of sounds obtained from the two ways makes our voice appear deeper. Now, when we hear our recorded voice, we only hear the voice which has traveled through our outer ear. Hence, our voice sounds different when recorded. Why is yawning contagious? Because everybody wants to sleep. No. There are a couple of theories which explain why yawning is contagious. One of them suggests that it is a sign of empathy. Empathy is the ability to understand and share others feelings. For example, when people around us are happy and smiling, they make a positive impact on us. Hence, we also feel good and begin to smile. Moreover, the closer we are to someone such as our parents or friends.