Lau Jia Yee (WINNER by lucky draw -
14th August 2009)
What causes volcanoes to erupt?
A volcano is an opening in the earth’s crust erupting gases and magma. Magma is formed when the lower crust or the upper mantle of the earth melts.
Volcanic eruptions are caused by
several factors. The first is the buoyancy of the magma. When rocks melt in the
earth’s crust forming magma, its mass remains the same, but the volume increases
considerably. This magma rises towards the surface due to its buoyancy. The
second factor is the pressure from the gases in the magma. Molten lava produces
gases such as sulphur dioxide and carbon dioxide. As the magma rises to the
surface, the pressure from the gases within it increases, resulting in a
volcanic eruption.
The third factor is the injection of a new mass of magma into an already filled
magma chamber. With a high volume of magma, the resulting high pressure creates
a volcanic eruption.
Yoo Lye Peng Kevin (WINNER by lucky draw - 24th August 2009)
There are many kinds of cancer, so why is there no heart cancer?
Cancer of the heart muscle can happen, it is simply very rare. Cancer arises from DNA
mutations in the cell, and is passed on by cell division. Heart cells generally don’t divide to
make new cells, except where there has been an injury. Also, unlike skin cells that are
exposed to ultraviolet rays and colon cells that come into contact with carcinogens in food,
heart cells are not usually exposed to elements that spark mutation. Therefore, there are
not many opportunities for cells in heart tissue to become cancerous.
Twitter user “Yipeng”
(WINNER by lucky draw -
28th August 2009)
Do stars really flicker?
Stars appear to flicker because the different layers of the Earth’s
atmosphere bend the light differently.
As the different pockets of air
move, the star seems to change in brightness. The same thing happens
when the air above a hot pavement shimmers.
Ling Huey Lin Joyce (WINNER by lucky draw -
4th September 2009)
Why are clouds grey during rainy weather?
Clouds are made up of water and dust from the atmosphere. Hot moist air rises up into the sky,
where it meets cooler air and condenses around dust particles to form water droplets. When the sun shines on the densely packed water droplets, the light gets reflected back out and the cloud appears white.
Over time, the water droplets collide into each other and merge to form larger and larger droplets.
As the cloud thickens even further it starts to block sunlight from passing
through and so appears
grey to us. The same cloud would appear white if seen from a plane flying above
because the aircraft
is in between the sun and the clouds. When the droplets are heavy enough they
fall as rain. Hence the association between thick grey clouds and rainy weather.
Yap Suat Hoon
Why can water be boiled below 100 Celcius?
Indeed water can boil below 100 degrees Celsius, and this will happen when the air pressure is lower than
normal. For example, on high mountains, the air is thinner and hence exerts a lower pressure, allowing
water molecules to escape across the water surface more easily. The result is that the water will “boil” at
temperatures lower than 100 degrees Celcius.
Vacuum distillation takes advantage of this phenomenon. By creating a partial
vacuum (sucking some of the
air out), water can be vaporized at a lower temperature, which means a saving in
the amount of heat that
needs to be employed.
Twitter user "Chillycraps"
Why does chilli taste spicy?
Chilli contains an odourless, flavourless substance called capsaicin, which stimulates the areas
of the skin and tongue that sense heat and pain. So when you eat something that contains chilli,
the brain receives a message that there’s a “fire” burning in your mouth, hence the distinctive hot,
peppery taste.
Scoville Heat Units measure how “hot” a chilli is. This measure, named after the chemist who
discovered it, refers to how much sugar-water is needed to dilute the chilli to a point where you
can no longer taste its spicyness. For example, a bell pepper has 0 units, while bird’s eye chilli
(the famous chilli padi) rocks the scale at about 50,000 to 100,000 units.
Yoo Lye Peng Kevin
What’s the natural way of severing the umbilical cord in animals?
Some animal mothers gnaw through the cord, separating the placenta from the baby animal.
Often the cord and placenta is eaten by the mother. Not only is it a useful source of nourishment,
eating it would prevent the smell from attracting scavengers or predators to the vulnerable new
mother and baby.
Chimpanzee mothers do not sever the cord at all, but simply nurse their babies along with cord
and placenta still attached until the cord dries and separates naturally, usually within a few days of birth.
Humans who practice this call it “lotus birth”.
Deshawn Toh
Why is there a loud "boom" when an aircraft reaches a certain speed?
That loud sound is known as a sonic boom. Objects moving through the air create pressure waves in
front and behind them. The waves move at the speed of sound in air, known as Mach 1, approximately
1225 kilometres per hour. When an object increases its speed, the waves are forced closer and closer
together, until they merge into a single shock wave when the object hits the speed of sound.
Sometimes vapour cones form around the aircraft as it approaches the speed of sound, the change in
pressure condenses water in the air as the aircraft passes. Thunder is a natural form of sonic boom,
created by the rapid heating of air when lightning is discharged.
Rachel Yeo An Lin
Why is ice clear and snow white?
Snow is made up of individual snowflakes, with plenty of air trapped
between the ice crystals. When
sunlight shines on snow the light beams
are immediately scattered in different directions, and then
all of the
light eventually gets reflected back out again, making it the same
colour as sunlight – white.
Ice, on the other hand, is made up mostly of frozen water, with very
little air trapped inside. This allows
light to travel through with
hardly any reflection. When the layers of ice get very thick, like in
glaciers, the
red light gets absorbed, giving glaciers a blue hue.
Catherine Ling
Why do octopuses/octopi need three hearts?
Octopuses are powerful swimmers, and have three hearts to help them
maintain a robust blood pressure.
They have one main heart, called the
systemic heart, and two smaller hearts located near their gills. The two
smaller hearts pump blood to the gills, dumping waste and loading up on
oxygen. This oxygen-rich blood is
then pumped back to the main heart,
where it gets distributed through the rest of the body.
They also have blue blood rather than red. Instead of hemoglobin which
makes human blood appear red,
octopus blood contains a different protein
called hemocyanin, making it appear blue.
Yoo Lye Peng Kevin
Why do cats have an inner eyelid as well as outer ones?
A cat’s inner eyelid is called the haw, or nictating membrane – you can
sometimes see a tiny triangle of
pink or white tissue in the corner of
the cat’s eye, especially if the cat is sleeping with its eyes partially
open.
The function of this membrane is to clean or lubricate the eye
surface. In the wild, a cat’s third eyelid serves
to protect its eyes
from possible injury as it hunts among the tall grass. When a cat’s
third eyelid is unusually
visible, it may be a signal that it is ill or
unwell.
Many other animals have a third eyelid. In fact, humans and primates are some of
the few mammals that don’t.
Jani Ong
Why do opposite sexes attract each other and how long is the span of attraction?
Studies have revealed that there are important chemicals involved in love and attraction. One such
chemical is the pheromone which is secreted by the body. It leads to feelings of attraction and thereafter,
dopamine and norepinephrine are produced by the brain to cause obsessive-compulsive behaviours.
Over time, vasopressin and oxytocin which are responsible for the formation of long term bonds interfere
with the dopamine and norepinephrine pathways, explaining the fading of passionate attraction. There is
no fixed span of attraction but on average, this fading of passionate love happens over a period of 6 months
to a year.
Joel Tan
Why can't we feel the earth moving?
The Earth moves at about 100,000 kilometers per hour around the Sun, which is at least a thousand times
faster than how fast we travel on an expressway. At the same time the Earth also spins on its axis at over
1600 kilometers per hour. Thankfully everything on Earth is moving along with us, so it doesn’t “feel” like
we’re moving. When we’re in a moving car, we feel it when the car is speeding up or slowing down, but not
when we’re cruising at constant speed. We feel the acceleration rather than the speed.
Sam Tan
Why do people tend to sneeze more in the morning when they wake up?
While you’re asleep your body temperature is lowered, and also dust accumulates in your nose.
Sneezing in the morning is the body’s way of warming up, and expelling the dust. If you’re allergic to
dust mites, and especially if the environment you slept in is dusty, you’re more likely to sneeze.
Having a hot drink before you get out of bed is one way of avoiding a sneezing fit in the morning.
