Page 47 - How It Works - Book of Amazing Answers To Curious Questions, 12

Science Q�
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How do the holes Why do we hiccup?

get in Swiss cheese? here are over 100 physiological reasons throat) shuts off the windpipe and this
T
as to what sets hiccups off, the most produces the 'hie' noise.
T o make cheese you need the help of common being expansion of the stomach and Scientists are trying to find the purpose of
bacteria. Different types of bacteria in movement of stomach acid into the hiccups. One theory is that they may have
different combinations give rise to the distinct oesophagus. After this then it could be an been useful for an ancestor of ours. Standing
variety of flavours in many cheeses. There are irritation of the thorax or the phrenic nerve on two legs gives us the advantage of using
various different types of bacteria used for (the nerve to the diaphragm). gravity to help digest our food, but four-legged
making Swiss cheese, the one responsible for The mechanism of a hiccup usually creatures have to digest horizontally which
the holes is called Propionibacterium involves a strong contraction of the means it's easier for food to get stuck. Some
shermanii. Once this bacteria is heated slightly diaphragm, the neck muscles and some other scientists think the lodged food could have hit
it reacts, forming bubbles of carbon dioxide surrounding muscles. Just after the a nerve responsible for triggering the hiccup
that become the final holes in the product. contraction begins we start to inhale, at which allowing the food to be swallowed. If this is the
The technical term for these holes is 'eyes'. point the glottis (a kind of fleshy trap door case then hiccups could have been highly
The size of these eyes can be controlled by the which separates the food and air tubes in your useful rather than just making you look daft!
cheesemakers by altering the acidity,
temperature and curing time of the mixture. One theory is that hiccups may have been
Generally, in most foods which require
fermentation, bubbles of carbon dioxide will be useful for an ancestor of ours
formed but most of the time they escape. The
procedure which goes into making Swiss � ....::::0
cheese means those bubbles remain trapped
inside which means there will be 'eyes' in the Why use salt Why do we
to melt ice on sometimes
final product.
the roads?
remember our
How do S water/ice. The melting point of ice under dreams?
alt lowers the freezing/melting point of
boomerangs normal conditions is zero degrees Celsius. T his is a very good question and it is one
stay airborne? Sea water, however, freezes/melts at -2.2 answer based on our current understanding
for which there is no satisfactory
degrees Celsius due to its high salinity.
As to why salt lowers the melting/ of the brain. One thing studies have told us,
S o we've covered why they come back, but freezing point of water, this is a bit more though, is that dreams seem to happen more
how do boomerangs stay up in the first
vividly and frequently during the REM (Rapid
difficult to explain without going into some
place? The two arms of the boomerang are complex chemistry. Basically water is made Eye Movement) stage of the sleep cycle,
like the wings of a plane in that the faster from Hp, and anything else which gets in which tends to occur roughly four to five
they move through the air the more lift they there, such as sodium in the case of salt, gets times in a normal night's sleep.
generate. Unlike plane wings they spin as they in the way and makes it harder for the Hp to It has been reported by several studies
move through the air and this combination of bond as ice. that you are much more likely to remember
spin and movement means that some parts Upon sprinkling salt onto ice, the salt first the dream you were having if you are
of the boomerang are moving quicker. dissolves into the liquid water surrounding woken in the middle of this REM cycle. So if
Because the boomerang is spinning the the ice causing the ice to melt. The salt can you would like to remember your dreams
aerodynamic lift occurs at different rates on only lower the melting/freezing point of more frequently, you could try setting your
different parts of the boomerang, as the water up to around -16 degrees. If the alarm clock to go off in the middle of your
wings of the boomerang are thrown at an temperature is below this point then salt is REM sleep cycle (likely to be near the end
angle the net lift is towards the centre of the ineffective and it would be better to pour of your night's sleep) and write down what
circle that the boomerang moves on. sand over the ice to help increase traction. you remember.

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