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Why do firemen crawl in smoke filled rooms? plus 9 more videos.. #aumsum

Topic: 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 won’t. 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. Don’t 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. Topic: Sublimation. Why do mothballs disappear over time? Wow. You have a nice collection of clothes. But have you kept mothballs to protect them? I had kept them a few months back below these clothes. Where did the mothballs go? I had placed them right here. Did you steal them? No No. I haven’t stolen anything. Mothballs disappear over time. Do you know why? It is because of a process called sublimation. During sublimation, a solid on heating. Converts directly into vapor without passing through the intermediate liquid state. Don’t lie. How is that even possible? See, I also hid a burger here many days ago. It did not disappear. Gross. Just throw that burger in the dustbin. Not all substances sublimate. Mothballs are made up of naphthalene. Naphthalene has very weak intermolecular forces. Because of these weak forces, the mothball which is made up of naphthalene sublimates. It changes its state from solid to vapor. Now, this vapor is either absorbed by the
fabric. It escapes into the atmosphere causing the mothballs to disappear over time. Topic: Ultrasound. Why is ultrasound used in sonar? Hey. Looks like you are searching for a treasure
hidden in a sunken ship. Why don’t you use a sonar? It will emit ultrasounds and help you locate
the ship. You know what. I have a better idea. No. A music system will make ordinary sound. So, it is of no use. Don’t fool me. I know that the music system is the right
choice. See. You are not able to find the ship. Now will you use a sonar? Look. You easily found the ship. Do you know how a sonar could locate the sunken ship? It was because of ultrasound. Ultrasounds are sounds having very high frequencies which start from 20,000 Hertz. So, is ultrasound used in sonar because of
its high frequency? You are absolutely correct. Due to its high frequency, an ultrasound can penetrate to a greater depth. Thus helping us to locate the depth of the sea, sunken ships, etc. But, I am not able to hear the ultrasound? It is because human beings can hear sound
frequencies from 20 Hertz to 20,000 Hertz. As ultrasounds have frequencies higher than 20,000 Hertz, we cannot hear them. Topic: Refraction of Light. Why does a pencil look bent in water? Wow. That was a very cool magic trick. Now check this out. Hey. Stop crying. Your magic wand is not bent or broken. Look. It is safe. But do you know why your magic wand appeared bent in water? It is because of refraction of light. Refraction of light is the change in direction of light when it passes from one medium to another obliquely. So, what do you think are the two media here? You don’t know. No worries. I will tell you. They are air and water. When the light rays coming from the tip of
the magic wand pass from water to air. They change their direction , that is, they get refracted. When these refracted rays reach our eyes,
our eyes trace them backward as straight lines. Due to this, the rays appear to come from
a point slightly above the original position. Hence, the magic wand appears to be bent in water. Similarly, like the magic wand, a pencil appears to be bent in water. Topic: Stomata. Why do water lilies have stomata on the upper side of their leaves? Don’t immerse that plant completely in water. You don’t have knowledge about anything. Water lily is an aquatic plant. So, I am keeping it totally under water. Yes, you are right. It is an aquatic plant, but it is not an underwater plant. Its leaves float on water. Don’t lie to me. How can leaves float? Fine. Don’t listen. Look. You spoiled it totally. Alright. Now don’t cry. To understand why this happened, you need to first learn about stomata. On the lower side of the leaves, tiny pores
called stomata are present. They help the leaves to take in carbon dioxide from air, during the process of photosynthesis. So, shall I place the plant upside down? No. We know that the leaves of water lilies float. Hence, if the leaves of water lilies would have stomata on their lower side. Then they would have been pressed against the water surface. As a result, the stomata would not be able
to take in carbon dioxide from air. Thus, the leaves of water lilies have stomata on their upper side. Where they easily get air and usually do not come in contact with water. Topic: Frequency. Why do women have shriller voices than men? Hey. Hey. That door will open only with a woman’s voice command. Don’t try to fool me. Now how will I enter? Don’t worry. Just trust me. A woman’s voice is shriller. So, speak as a woman. Could you please. Look. The door opened. This happened because of frequency. Frequency is the number of vibrations per
second. More is the frequency, shriller will be the
voice or sound. Explain it to me quickly. I can’t wait. Alright. Alright. In humans, sound is produced with the help
of vocal cords. However, the length of vocal cords of women and men are different. A woman’s vocal chords are about 15 millimeters long. While a man’s vocal chords are about 20 millimeters long. As the vocal chords of a man are comparatively longer. They vibrate less per second, producing sound having low frequency. However, the vocal chords of a woman being short vibrate more per second. Thus producing sound having high frequency. As the frequency of sound is higher, women have shriller voices than men. Topic: Diffusion. Why can we smell hot food from a distance? Hey. Looks like you have lost your way. No. I know the way. Fine. Don’t listen. See, I told you. Now listen to me. There is a restaurant next to your house where hot sizzling food is available, right? Yeah. Yummy. Follow its smell and you will reach home. I have reached home. Do you know how the smell of that food reached you? When food gets cooked, it releases some aromatic gases into the air. The molecules of these gases spread and mix with air molecules. When this air reaches our nose, we get the
smell of food. This process of spreading and mixing of a
substance with another substance is called diffusion. But then, why couldn’t I smell the food inside my house from a distance? This is because that food had become cold. On heating food, the molecules of its aromatic gases gain kinetic energy and start vibrating faster. They spread and mix easily into air, leading
to an increased rate of diffusion. As the food gets cold, the temperature of
the aromatic gases decreases. The kinetic energy of molecules decreases
and they do not vibrate as much anymore. Thus, the rate of diffusion decreases and
we cannot smell the food from a distance. Topic: Density. Why does an iron nail float on mercury and
sink in water? Looks like you are stuck in the middle of
a huge sea. Really. I had no idea. No. Don’t take the nail into water. It will sink. Take the nail into mercury. It will float and help you reach the shore. You are bluffing. How will the nail float in mercury? Please listen to me. See. I warned you. Will you now use the nail in mercury? Yeah, Yeah. I will. Do you know why the iron nail sank in water and floated on mercury? It is because of density. Density is the measure of mass present per
unit volume. Lesser the density of the fluid. Lesser will be the upward force exerted by the fluid on the object placed in it. In the first case. The iron nail sinks in water because the density of water is comparatively less than the iron nail. As water is less dense, the upward force exerted by it on the nail is less. Hence, the nail sinks in water. However, in the second case, as the density
of mercury is comparatively more than the iron nail. The upward force exerted by mercury is more. Hence, the nail floats on mercury. Topic: Earthing. Why do buildings have lightning rods? I know. They are used to dry clothes. No. They are used for earthing. Earthing means digging the earth, right? No. Earthing is the process of transferring charge from a charged object to the earth. It is done with the help of this lightning
rod. A lightning rod is a metal rod whose lower
end is fixed to a copper plate buried deep in the earth. While upper end has spikes. But why is it called a lightning rod? This is because it protects us from lightning. Lightning is a flow of massive charge. It can damage an entire building and harm
the people living in it. Hence, to protect them. The lightning rod transfers the massive charge from the lightning to the earth safely. Topic: Rust. Why is oxalic acid used to remove rust stains? Hey. You have a beautiful antique lamp. But look. It has a rust stain on it. No. Don’t clean the rust stain with water. Instead, use this oxalic acid. Oxalic Acid. You just don’t want my lamp to be nice and
shiny, do you? No, I am helping you. Why don’t you listen? Because, I know that you are making a fool
out of me. Fine. Go ahead. See. I had told you. Now will you use the oxalic acid? Look. The stain disappeared. Do you know how this happened? Wait. Let me tell you. Rust is hydrated iron oxide. It is formed when iron reacts with oxygen
and water. Rust is insoluble in water. Hence, it is quite difficult to remove rust
stains. So, how does oxalic acid remove the stain? Does it have some supernatural powers? Absolutely not. Oxalic acid reacts with rust to form iron
oxalate complex ion. Iron oxalate complex ion is soluble in water. Thus, it can easily be washed away, helping
us remove the rust stain.


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