Page 142 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

How does salt

melt ice on the

roads?

e spread granulated salt on icy roads
W because it lowers the freezing and
melting temperature of water. When water
cools to zero degrees Celsius (32 degrees
Why are bicycles much more Fahrenheit) or below, it freezes into ice. But
when you add salt, the water must be at a
much lower temperature to freeze. For
stable when moving? example, a 20 per cent salt solution would
freeze at -16 degrees Celsius (three degrees
Fahrenheit). If you sprinkle salt on ice that’s

here is no definitive explanation behind aligns the bikes wheels a bit like when formed on the road, it will dissolve into the
Ta moving bike’s uncanny ability to stay pushing a shopping cart. Researchers, liquid water film on the surface of the ice

upright. Experts agree that it is linked to however, disproved these theories in 2011 by and ultimately melt it. There is a limit,
bikes’ ability to steer into a fall and right building a bike which negated both effects. however; if the road temperature is lower
themselves, with even riderless bikes able to A pair of counter-rotating wheels cancelled than minus-nine degrees Celsius (15 degrees
recover from a sideways push. For a long out the gyroscopic effect and the steering Fahrenheit), the salt cannot penetrate the
time, it was believed that the wheels axis lay behind the front wheels, yet the surface of the ice to begin the process of
created stability through the gyroscopic moving bike was still stable. The research melting it. Some places add calcium fl uoride
effect: the tendency for a spinning object to team concluded that although both effects to their road-salt mixture at these colder
resist movement in certain directions. A may have an impact, neither were vital to a temperatures, which allows for melting at
second idea was that the direction of travel bike’s stability.
slightly lower temperatures.

Why does tarmac

have that mirage

effect, even if it’s not a

particularly hot day?

lthough they’re often associated with deserts
Aand summer temperatures, it doesn’t have to
be a particularly hot day for you to see a mirage on
dark tarmac – just a sunny, dry one. Mirages are
caused by waves of light passing through layers of
air that have different densities, then refracting – or
bending – towards the densest layer of air. In an
inferior mirage, the layer of air on the surface is
warmer than the air above it, creating an image
below that of the actual object. This is why you can This image was taken in
Apeldoorn, the Netherlands, in
often see mirages on road surfaces because tarmac May, when the average high
heats up quickly on a sunny day. temperature is 13°C (55.4°F)

142 How It Works