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  • It's AumSum Time

  • Why are manhole covers round?

  • Because they copied my shape.

  • No

  • Manhole covers are quite heavy.

  • So, round-shaped covers can be rolled easily from place to place.

  • Also, round covers can simply slide and fit into the hole.

  • But, to fit square or triangular manhole covers properly.

  • They must be precisely aligned with the edges and angles of the manhole.

  • Now, the manhole has a small lip around the rim of the hole.

  • This lip makes the opening smaller than its cover and prevents the cover from falling into the hole.

  • But, a square or rectangular cover can still fall into the hole, if inserted diagonally.

  • Why?

  • Because their sides are always smaller than their diagonals.

  • A round cover won't fall into the hole.

  • Because no matter how you place it, the cover is always wider than the opening.

  • Topic: Respiration

  • Why is it not good to sleep under a tree at night?

  • Hey.

  • You look so tired.

  • Why don't you take rest here?

  • No.

  • Please don't sleep under that tree!!

  • It is quite harmful.

  • See, you are not able to breathe properly, right?

  • Do you know why?

  • Wait, I will tell you.

  • This is because during the day, in the presence of sunlight, plants take in carbon dioxide.

  • Release oxygen in the process of photosynthesis.

  • However, they even respire simultaneously.

  • In this process, plants take in oxygen and release carbon dioxide.

  • But the production of oxygen is more than the production of carbon dioxide.

  • Hence, if we sleep under a tree during daytime, we may get a good amount of oxygen.

  • Thus giving us a nice sleep.

  • However, at night, plants do not perform photosynthesis due to the absence of sunlight.

  • But respiration still goes on.

  • Hence, as compared to oxygen, the proportion of carbon dioxide around the trees is more.

  • Thus, if we sleep under a tree at night, we may feel suffocated due to lack of oxygen.

  • Moreover, inhalation of excess carbon dioxide is harmful to human beings.

  • Therefore, it is not good to sleep under a tree at night.

  • Topic: Paper cut.

  • Why do paper cuts hurt so much?

  • It is because paper hates us.

  • No.

  • We use our fingers and hands to sense our surroundings.

  • Hence, they have more number of nociceptors than any other parts of our body.

  • Nociceptors are pain receptors that respond to change in pressure, temperature, etc.

  • Now, the edges of the paper are not smooth but are rough or jagged.

  • They are like a saw.

  • Absolutely.

  • Hence, sometimes when we rub our hands or especially fingertips against the edges.

  • It cuts themlike a saw, activating the nociceptors.

  • Now, as there are more nociceptors on our hands, we feel more.

  • In addition to this

  • The paper cut might also have fragments of paper containing chemicals.

  • Which may irritate the skin and thus increase the pain.

  • How do igloos keep you warm?

  • I'm a little busy.

  • So, I'll tell you about it later.

  • Alright.

  • I'll explain.

  • Heat is a form of energy present in our body.

  • When the temperatures around us are low, we begin to lose heat.

  • The more we lose heat, the colder we feel.

  • Now, although igloos are made up of blocks of compressed snow, they keep us warm.

  • Stop bluffing.

  • How's that possible?

  • Compressed snow has air trapped in it and air is a bad conductor of heat.

  • Hence, the heat given off by our body does not get lost from the igloo.

  • It stays in the igloo, thus keeping us warm.

  • Besides this, we know that warm air rises up and cold air sinks to the bottom.

  • Hence,

  • During night,

  • Eskimos, that is, people living in igloos sleep at the uppermost part of the igloo to stay warm.

  • Why smoking makes people look old?

  • So that we look more experienced and intelligent.

  • No.

  • Smoking makes people look old because things like cigarettes contain nicotine.

  • Nicotine is a vasoconstrictor which means it narrows our blood vessels.

  • Restricting the blood supply.

  • When the blood supply is restricted, our cells don't get the required oxygen and nutrients.

  • As a result, our skin becomes dry and discoloured.

  • In addition to this, the collagen and elastin fibers which keep our skin firm and elastic.

  • Begin to break down much faster, leading to saggy and wrinkled skin.

  • Also, when we smoke, we purse our lips and squint our eyes.

  • Regularly repeating these actions may also cause wrinkles on our lips and around our eyes.

  • In this way, smoking makes our skin dry, saggy and wrinkled, thus making us look old.

It's AumSum Time

Subtitles and vocabulary

B2 H-INT US oxygen sleep paper hole carbon dioxide dioxide

Why are Manhole Covers Round? | #aumsum

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    AumSum   posted on 2019/04/06
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