The boiling point of water depends on atmospheric pressure.
It takes much longer to cook things in the hills than in the plains. Because in
the hills, the atmospheric pressure is lower than that in the plains and
therefore water boils at lower temperatures.
Food is
cooked faster in the pressure cooker. Because due to high pressure, the boiling
point of water is raised.
The cover of
a solar cooker is made of glass. Because glass allows sunlight in the
container but does not allow heat radiation out of it.
Water in a
flask is fitted using a cork with a narrow tube. When the flask is heated, the
level of water in the tube first falls and then rises.
In cold
countries, alcohol is preferred to mercury as a thermometric liquid. Because alcohol has a very low freezing point.
On heating a
circular disc with a circular hole at the centre, the diameter of the hole will
increase.
When a
certain mass of liquid is heated in a glass flask, the liquid level falls at
first and then starts rising.
If water in a lake were to behave like other liquids, then in extremely cold weather, it
would freeze from bottom to top.
If the
temperature of the top of a frozen lake is -150 C, the temperature
of the water in the lake in contact with the ice layer is 00 C. The
fishes can survive inside a frozen lake because, at the bottom of the lake,
there is 40 C.
When water
is cooled from 80 C to 00 C its volume decreases up to 40
C and then increases.
An iron
hammer, lying in the sun appears much hotter than its wooden handle. Because iron is a good conductor of heat.
Mica can be
classified as a good conductor of heat and a bad conductor of electricity.
The freezer
in the refrigerator is fitted near the top. So that it can cool the whole
interior by setting up a convection current.
By the
process of radiation, the heat is transmitted from the filament of an evacuated
electric bulb to the glass.
Woollen materials
keep us warm in winter. Because they do not allow our body heat to escape.
A Pyrex
tumbler does not crack when hot water is poured into it. Because Pyrex does
not expand much on heating.
In a cup,
tea cools from 700 C to 600 C in exactly one minute. It will
cool from 400 C to 300 C in more than one minute.
The surface
of water in a pond remains cool even on a hot day. Because water evaporates at
the surface and evaporation causes cooling.
Read more:
Some interesting facts about mechanics for learners
Read more:
Some interesting facts about mechanics for learners
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