字幕表 動画を再生する 英語字幕をプリント It's AumSum Time. Can you guess the title of my next video? Hurry up. Write your guess in the comments section below. What is depression? It is a 5 star hotel deep underwater. As usual. You are wrong. In our life, all of us feel sad or depressed for some time. But that doesn't mean we have depression. Many doctors use a manual named Diagnostic and Statistical Manual of Mental Disorders to diagnose depression. It has a list of symptoms which include sadness, worthlessness, hopelessness, changes in appetite, suicidal thoughts, sleep problems, etc. If we have five or more of these symptoms for at least two weeks, then doctors diagnose us with depression. The exact causes of depression are unknown. But studies suggest that people who have depression may have a smaller hippocampus. An area of the brain that regulates emotions. Moreover, genetics might also play a role. Studies have shown that a variation in the serotonin transporter gene makes us more prone to depression. Environmental factors such as coping with the death of our beloved ones, traumatic events, etc. can also cause depression. Topic: Buoyancy. Can you drown in the dead sea? Your answer must be yes, right? You must be thinking that anybody who cannot swim will obviously drown. Whether it is a swimming pool or the dead sea. However, that is not 100% true. Confused? Let me explain to you. When an object is partly or wholly immersed in a fluid, an upward force is exerted by the fluid on that object. This tendency of the fluid to exert an upward force on the object is called buoyancy or upthrust. This upward force is called buoyant force. So, do you finally get it? Let me give you one more example. Place a piece of wood in water and push it downwards. What do you observe? It seems like something is pushing the piece of wood upwards, right? Water exerts an upward force on the wood. That is why the wood is getting pushed upwards. This force is called buoyant force and the tendency of water to exert that buoyant force is called buoyancy. Dead sea has a huge amount of salt dissolved in it as compared to any other sea or ocean. The presence of this salt increases density of water present in the dead sea. Higher density leads to greater buoyant force. As the dead sea has very high density, it exerts enough amount of buoyant force to make us float on it. So, if we can float on the dead sea, we are definitely not going to drown in it. Topic: Latent heat of vaporization. Why does steam cause more severe burns than boiling water? It is because steam is jealous of boiling water. No. It is because of latent heat of vaporization. Latent heat of vaporization is the amount of heat energy required to change a unit mass of liquid into vapor at atmospheric pressure at its boiling point. Trust me. Everthing just went over my head. Alright. I'll explain it to you. Boiling water contains only a specific amount of heat energy required for it to boil. However, as steam is formed from boiling water. It contains the heat energy of boiling water, along with the latent heat of vaporization. Hence, as steam has more heat energy, it can cause more severe burns than boiling water. Why do your eyes turn red in the pool? It is because of chlorine. Chlorine is not the main reason for this. Chlorine is added to water of swimming pools because it is a disinfectant. It helps kill germs, thus keeping water germ-free. In fact, the main reason for our eyes to turn red is the presence of our bodily fluids like urine and sweat in the pool. Urine and sweat contain nitrogenous compounds like urea. Urea reacts with chlorine present in water, forming chloramines. Now, if we regularly clean the swimming pools, then we can prevent the production of chloramines. But if the pools are not cleaned, then the chloramines formed can irritate our eyes, thus making them red. In addition to this, chloramines can evaporate from water. Inhaling these chloramines for a long period can result in coughing, asthma and other health problems. What is a stroke? It is a new style of haircut. No. Through a complex system of arteries, our brain gets a continuous supply of oxygen and nutrients with the help of blood. The cells of our brain alone use more than 20% of oxygen in our blood. Hence, if the blood doesn't reach the brain cells, they can begin to die, thus giving us a stroke. The most common stroke is Ischemic stroke. Ischemic strokes occur when the arteries supplying blood to the brain get blocked. Like the roads get blocked in a traffic jam, right? Indeed. Due to bad lifestyle choices and stress, fats and cholesterol gradually start building up in the arteries. Thus, narrow them. If this build up ruptures, a clot may form blocking the complete artery. As a result, the brain cells begin to die due to lack of oxygen and nutrients. Thus, giving an Ischemic stroke.