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. No. 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. No. 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: Speed of sound. Why does sound travel faster in summer than in winter? Wow. That was an amazing trick. The television switched on immediately after you clapped. I know. This is one of my favorite tricks. Now, I bet you that the television will not switch on instantly after your clap. This time I am going to prove you wrong. See. I told you. I lost again. Do you know why the sound took more time to reach the television? This is because the speed of sound decreased. Speed of sound depends on the temperature of the medium. Higher the temperature of the medium, more
will be the speed of sound and vice versa. So, in this case, what do you think is the
medium? Are you kidding me? I don't know. No Problem. I will tell you. In this case, air is the medium. During summer season, the temperature of air increases. At higher temperature, the molecules of air have more kinetic energy. Hence, they vibrate faster leading to increase in speed of sound. Now, during winter season, the temperature of air decreases. With decrease in temperature, the kinetic
energy of the molecules also decreases. Hence, the molecules do not vibrate much. As a result, the speed of sound decreases during winter season. Topic: Ignition Temperature. Why does a match light when you strike it? Why don't you use a match instead? You will be able to light the bonfire easily. No. I don't believe you. Try it. Look. I told you. Dude. That was awesome. This happened because of low ignition temperature. Ignition temperature is the lowest temperature at which a combustible substance starts burning. Lower the ignition temperature, more easily
will it catch fire. Now, a match head contains antimony trisulfide and potassium chlorate. Enough. I know how to use it now. No. The match will not light on any surface. The rubbing surface of a matchbox has powdered glass and red phosphorus. On striking the match against it, friction
is caused. Friction generates heat, converting red phosphorus to white phosphorus. White phosphorus has a very low ignition temperature. It immediately ignites in air, producing heat and light, thus beginning the process of combustion. The heat produced breaks down the potassium chlorate present in the match head, releasing more oxygen. This oxygen combines with antimony trisulfide which is also in the match head and keeps the flame burning Topic: Wavelength. Why red is used as a danger signal? Well. Because my teacher said so. As usual, you are wrong. The major reason for red to be used as a danger signal is its wavelength. I know. Wavelength is the distance between two sea waves. No. In the wave theory of light, the distance between successive crests or troughs is called wavelength. Longer the wavelength, lesser will be the scattering of light. Now, among the colors of visible light, red has the longest wavelength. Hence, it is least scattered by the atmospheric particles. As a result, whether it is fog or smoke, red light passes comparatively easily through them. Thus, it can be seen from maximum distance, making red color the right choice to convey any danger. Topic: Bad Conductors of Heat. Why are two thin blankets warmer than one
thick blanket? Because two chocolates are better than one. No. To understand this, we need to first learn about bad conductors of heat. Bad conductors of heat are the materials which do not allow heat to easily flow through them. Air, wood and glass are some examples of bad conductors of heat. In these examples, is our train conductor included as well? Just listen. A thick blanket allows much of our body heat to escape into the atmosphere. However, when we use two blankets one on top of the other, air gets trapped between them. This air being a bad conductor of heat, does not allow our body heat to easily flow into the atmosphere, thus keeping us warm. Topic: Comets. Why do comets have tails? Maybe because, like monkeys, they can hang themselves on trees. No. Let me explain. A comet is a mixture of rocks, dust and ice. This ice is basically frozen water and frozen gases. When a comet approaches the sun, it starts to heat up converting ice directly into gas and releasing the trapped dust particles in space. So, you mean a comet has two tails. Absolutely. Stop bluffing. No. It is true. The ultraviolet radiations from the sun ionize the gas and the solar wind carries this ionized gas away from the sun, forming an ion tail. Whereas, the light from the sun exerts pressure on the dust particles and pushes them away, creating a dust tail. Topic: Lateral Inversion. Why is ambulance written in reverse? Maybe because there is some secret code hidden in it. You're just impossible. It is because mirrors form laterally inverted images. Lateral inversion is a phenomenon due to which the left side of an object appears to be the right side in the mirror and the right side appears to be the left side. Which hand are you raising now? Ok, Don't get angry. Let's get back to the question. We know that ambulance is an emergency vehicle. Hence, when the driver of the front vehicle
will see the ambulance in the rear-view mirror. He will see the laterally inverted image of the word and thus read it correctly, giving way to the ambulance.
