Page 39 - What Where Why - 8

Unit-V
fact-O-pedia
Science & fact-O-pedia
Technology 32
Everyday Science

Science is involved in our daily lives without us knowing.

Let's read about some phenomena that take place in our daily lives.

1. How does water remain cool in an earthen pot?
The water kept in an earthen pot remains cool even in summer because
of evaporation. An earthen pot has many tiny pores in its wall, which
causes some of the water molecules to seep out. This water evaporates
and takes the latent heat, i.e. the heat from the water inside the pot
along with it, keeping the water inside cool.

2. Why does a piece of metal sink, but a ship made of it doesn't?
It is due to the concept of density. A piece of metal is dense, i.e. it is
heavier than the weight of water it is able to displace. Whereas, a ship
is designed in such a way that its overall weight is less than the weight
of water it can displace, thus keeping the ship afloat.

3. Why does our breath smell after sleeping?
While sleeping, our saliva production decreases, leaving us with
a dry mouth, which results in bacteria build-up, which has a
distinctive smell. This may worsen if you sleep with your mouth
open.

4. Why does your voice echoes over mountains?
When we speak, sound waves leave our mouth. These sound waves
travel through air and bounce back from hard surfaces. If these surfaces
are at a large distance such as mountains, the reflected sounds reach
back our ears at different times, producing an echoing effect.

5. Why does the Sun appear red at sunset and sunrise?
The Sun appears red at the time of sunset and sunrise due to the
scattering of light by small particles of dust or smoke near the surface
of the Earth. The light travels relatively without hindrance and that is
why the Sun appears red at the time of sunset and sunrise.

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