SHUTTERSTOCKWHY DO BLACK CATS
BRING BAD LUCK?
Fear of black cats came to Europe
with Christianity in the early
Middle Ages. Unlike other
animals, cats can see and hunt in
the dark, and so, Christians believed
that cats were in collusion with
witches and devils. Cats came to
symbolise dark powers – and black
cats were particularly dreaded.The boiling point of water depends on air pressure and
the surroundings. The pressure at sea level makes
water boil at a temperature of 100 degrees C. On a
mountain peak, the pressure is lower, and so is the
boiling point of water.
That is so because water molecules can
more easily escape the water surface of the
pot, when the atmospheric pressure
pushes less "on to" the water. So, water
will evaporate faster at a lower
pressure – a process known as boiling.
In principle, water could boil at room
temperature, if the air pressure were
sufficiently low.
However, potatoes are not cooked
just because the water boils. The root crop
requires a high heat supply to be thoroughly cooked.
Having reached the boiling point, the water
temperature does not rise any further, and so, the
potatoes will not get as much heat-energy per minute
on the mountain.
This means that potatoes cook (by boiling) faster
at sea level, even though it will take a tiny bit longer
to bring them to the boil.Water boils faster in thin
mountain air, but lower water temp
means food takes longer to cook.Ask Us
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