Topic: Air Pressure.
How do straws work?
They work very hard.
No.
Straws work because of air pressure.
Is it similar to acupressure?
No.
Air pressure is the weight of air pressing down on earth and all other objects present on it.
Now, when a straw is in a liquid, the air pressure upon the liquid in the glass and the air pressure upon the liquid in the straw is similar
Causing the levels of liquid to be almost equal.
However, when we drink the liquid through straw, we first inhale causing the air from the straw to flow into our lungs.
Now due to absence of air, the air pressure in the straw decreases.
Hence, the air pressure present on the liquid of the glass pushes the liquid into the straw.
Causing it to move upwards and thus, helping us drink.
Topic: Archimedes principle.
Why do ships float?
Good question.
Give me minimum five years to unravel its mystery.
Alright.
Don't bother.
To answer this question, we need to understand Archimedes' principle.
Archimedes' principle states that an object partly or fully immersed in a liquid, experiences an upward force called buoyant force which is equal to the weight of the liquid displaced by it.
It is too complicated.
Ok.
Wait, I will explain.
A ship has a long and wide base due to which the amount and the weight of water displaced by it increases.
Now according to Archimedes' principle, the
buoyant force is equal to the weight of displaced liquid.
Hence, as the weight of displaced water increases, the buoyant force that is the upward force exerted by the water increases, making the ship float.
Topic: Blushing.
Why do we blush?
I don't know.
When we are embarrassed, ashamed or shy, we blush.
Blushing is governed by our sympathetic nervous system.
Its functioning is not under our control.
What?
I cannot control my own sympathetic nervous system?
Absolutely.
Now, when we are ashamed or shy, it causes us immediate stress.
When something causes immediate stress, our sympathetic nervous system considers 
it as a threat.
To defend the threat, this system orders our adrenal glands to release a hormone called adrenaline.
Adrenaline speeds up our breathing rate.
It expands the blood vessels so that more blood and oxygen can be reached to our body parts, thus preparing our body for fight or flight.
Now, as the blood vessels on our face are very close to our skin surface, they make our face appear red, that is, we blush.
Topic: Human Hair.
Why do we get white hair?
Because we cannot get blue hair.
No.
Our hair is basically made up of keratin, a colorless protein.
Hence, before our hair comes out of the skin, it is almost white.
How's that possible?
I had black hair during childhood.
Don't worry.
I will explain.
Our hair grows from hair follicles.
A hair follicle contains melanocytes which
produce melanin.
Melanin is injected in the keratin cells during the growth of our hair.
This melanin gives color to our hair.
Now, the color of our hair is dependent on the type of melanin injected.
Eumelanin makes our hair black or brown while pheomelanin makes our hair red or blond.
However, as we grow old, the melanocytes decrease the production of melanin.
Thus, less melanin is injected in hair, causing them to eventually turn white.
Topic: Kidney Stones.
What causes kidney stones?
Swallowing a stone?
No.
Our kidneys filter blood by removing waste
from it in the form of urine.
Urine consists of water, urea, uric acid and
ions like calcium, sodium, oxalate and potassium.
However, when some of these constituents such as uric acid, calcium and oxalate ions increase in the urine.
They bond together forming kidney stones or renal calculi.
One of the most common kidney stones is calcium oxalate.
So, can I use it to build my house?
Just listen.
Generally, the kidney stones are small.
Hence, they pass unnoticed through the urinary tract.
However, sometimes these stones become so big that they start to scratch walls of the urinary tract and may block the path of the urine, thus causing immense pain.
Topic: Human tongue.
Why does our tongue stick to a frozen pole?
Maybe our tongue has a magnet in it.
No.
Our tongue is always covered with saliva which is about 99% water.
During cold weather, heat from our warm blood is regularly supplied to our tongue, preventing the saliva from freezing.
Now, a metal pole is a very good conductor
of heat, that is, it conducts heat very easily.
It's so kind hearted.
Just listen.
During cold weather, the metal pole becomes frozen and does not have heat in it.
Hence, when we keep our warm tongue on the frozen pole, it draws heat from our tongue faster than the blood can replenish it.
Due to lack of heat, the saliva freezes and
forms ice, causing the tongue to stick to the frozen pole.
Topic: Earthquakes.
What causes earthquakes?
I, me and myself.
You show off.
An earthquake is violent shaking of the earth's crust.
The earth's crust is a hard outer covering made up of many pieces called tectonic plates.
These plates are always moving.
However, the motion is very slow.
In a year, they move only 2 to 5 cm.
My hair grows faster than their movements.
Absolutely.
Mostly when these tectonic plates move, they brush against each other without causing great damage.
However, sometimes they get stuck and cannot easily slide against each other.
But the plates still keep pushing, thus creating pressure.
Eventually, the pressure builds up so much that one of the plates suddenly moves above the other, or they may crash into each other.
Causing the crust to shake violently, thus creating an earthquake.
Topic: Rain.
Why does rain smell?
Maybe it applies a special perfume.
No.
Rain is just water and water doesn't have
any smell.
So, what's that smell?
The distinctive smell which frequently accompanies the first rain after a dry weather is scientifically called petrichor.
It basically comes from plants and bacteria
called actinomycetes which live in the soil.
Now during a long dry spell, the plants release oils into the soil to block other seeds from germinating, thus reducing competition for water.
Whereas, the actinomycetes produce a chemical called geosmin.
Now when rain hits the ground, it brings up
the oils and geosmin which then mix with air.
The combination of this geosmin along with
the plant oils form the smell which we receive after the rain.
Topic: Tooth decay.
What causes cavities?
A black sketch pen.
No.
Our mouth contains billions of bacteria which live on our teeth, tongue, etc.
Most of these bacteria are usually harmless.
Just like me, right?
Now listen.
A tooth consists of enamel, dentin and pulp.
Enamel is mostly made up of minerals.
Dentin is a layer underlying the enamel.
Whereas, pulp has blood vessels and nerves.
Now, when we eat foods containing sugars,
some of these bacteria feed on the sugars producing acid.
This acid starts to dissolve the minerals
of the tooth enamel, causing tooth decay.
Usually, our saliva restores these minerals,
thus preventing further decay.
But if we continuously eat sugary foods, then our saliva cannot keep up, causing the bacteria to pass into the dentin and then eventually into the pulp, thus creating cavities.
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 them like a saw, activating the nociceptors.
Now, as there are more nociceptors on our
hands, we feel more pain.
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.
