How the Metric system started?
Metric system was invented in France in 1791. Since the change was started from
measuring the length, that is why they chose the Latin word "Meter"
which means "measurement". So the whole system of measurement was named
as "Metric" system. Now, how long was the meter? In the beginning it was
equal to Earth's circumference - 1/40,000,000. It was written on a rod and kept
securely in a museum. Later, no relation could be established between these two.
Because of its destruction in any given circumstances, that measurement was transferred
to those natural measures which do not change. Since 1983, a meter's length is equal
to the length which light crosses in 1/299,792,458 second - about three hundred millionth
part of a second. Later on the basis of this measurement other measures were decided.
A normal man walks 1.5 meter per second. Marching soldiers walk 2 meters per second. A
fly's flying speed is more than the walking speed of man - 5 meters per second. On the
other side, a snail walks only 1.5 mm in one second, and tortoise walks about 2 cm in one
second. If you want to fly with cheel, you will have to take an aeroplane. Man-made
rockets fly only 8 km per second.
Sea in which you cannot drown
There is a Dead Sea in Philistine in which a
man cannot drown. Because it has so much minerals that its water is heavier than the normal
sea water. Normal sea water has less than 4% minerals, while in this sea there are 24% or
more minerals. That is why if somebody jumps in to it, he cannot drown.
How do you see the colors?
Color is those rays of the light which our eyes can see. And colors can be seen only
in the light. Where there is no light, there is no color. You see only those colors
which are not absorbed by the surface of the object.
Why the sky is red at sunrise and sunset?
Red color spreads in the sky at the time of sunset. It looks beautiful. But it
is not because that the Sun is red. If you see the Sun, the Sun is not red. At
this time these colors spread because of the distance through which the Sun rays
have to go through. As much the Sun will be down, the same distance the rays will
have to travel through atmosphere. Violet, blue and green colors are not absorbed
by the atmosphere while red color is more unabsorbed - about ten times, and red and
yellow colors are decreased too, that is why only red and yellow colors are seen
in the sky.
H. G. Wells has written
in one of his novels that a bullet went up to 70 km and came back in a few minutes.
What will happen if a well is dug through the Earth, and you travel through that well?
Since there is no bottom of the well, you will be safe. You will not stop in
the center of the Earth too, because when you will reach near it your speed
will increase (gravitation will decrease when you reach the center of the Earth) -
about 8 km per second, and you will continue to fall until you come out of the
well on the other side of the Earth. Now after reaching on the other end, if
you do not hold something tightly, you will again start falling with a hop. A
both-way journey will take only 1 and 1/2 hours. (On the center of the Earth
weight decreases, because gravitation works around the object not below the
You sit on a chair, with straight back and legs with 90 degree angle on the
ground. Now you try to get up without bending, you cannot get up. Because you
can only get up when your feet or back are not at 90 degree angle. This means
a thing cannot turn till it is making a 90 degree angle line reaching up from
its base. that is why the Pissa Leaning Tower is not falling down.
No two snowflakes are same
Do you know that no two snow flakes are same in design and they are white, not
colorless. Sometimes one snow flake can be of 3 cm diameter. In fact its size
depends on temperature, if temperature is low then flake size will also be small.
City in the sky
What is mirage? A thirsty man sees
water in the desert, on a warm day as you reach near the hill it seems that the
road is wet, even in the sea you see ships in the sky. These are the examples
of mirage. The most famous mirage is in Mesina in Sicily. The whole Mesina city
is reflected in sky and forts flying slowly in the air.
Distant green hills seem to look blue, why? Many kinds of particles - dust, ash,
smoke etc, swim in the air. When sunlight falls on them then different colors of
light refract from them. Blue and violet colors are of more temperature, so they
refract more than the green, yellow and red which are of low temperature, that is
why hills look blue.
Water boils at low temperature on hills, why?
As much higher we go, the temperature goes down, so the water will also boil
at as much lower temperature.
How much high temperature a man can tolerate?
Whatever you think, a human being can tolerate more than that heat. It is found
that in the cabins of travelers traveling in the Bay of Iran, temperature reaches
up to 50 degree C. The highest temperature in the world has been recorded in the
Death Valley of California - 56 degree C. It is found by experiment, that in dry
air, a man can tolerate 160 degree C temperature - temperature more than the boiling
Ice takes more space than water
Normally things shrink when get cold, but surprisingly water expands when frozen.
How much rate? It is 10%. So if you are freezing 9 quart water, it will convert
into 10 quart ice. On one side, this technique can burst water pipes, on the other
side it is used to break rocks in mines. And because ice is lighter than the water,
it floats. So in rivers etc. when upper layer of the water is frozen, the lower part
is still liquid and fish can live there easily, or on the other hand, you think that
you can skate on that ice but as you go on the ice, the ice breaks and you fall down
in the cold chilly water.
Why the red color light used for STOP signs?
Red color light can be seen from a long distance, while blue, green or violet
light cannot be seen so far. Because when light passes through the glass, whichever
color has longest wavelength refract the least and whichever color has the shortest
wavelength refract most. That is why red color is used in rail signals. even in fog
and storms red color rays refract least and that is why can be seen from a long distance,
while blue, green and violet cannot.
Does the Sun change its color?
Why the Sun looks yellow color at the time of sunrise and sunset? Although all seven
colors start from the Sun, but in the atmosphere blue and violet color rays refract
more and red and yellow color rays less. That is why red and yellow colors dominate
and sun looks more yellow. Since at the time sun rise and sunset the rays have to pass
a long distance, yellow color rays refract more and leaving the red color and all other
color rays in the atmosphere.
See the blue ink letters black
If you see the blue ink letters with red color glasses they will look black. Why?
Because only red rays can pass through red glass, not the blue ones. and since there
is no light there, in the absence of the light blue letters look black.
Rainbow has seven colors in it - violet, indigo, sky blue, green, yellow, orange
and red popularly known as VIBGYOR or ROYGBIV). When you see a rainbow you will
find the violet color at the lowest and red color at the top, because red color
refract the most. To appear this, the Sun, the spectator's eyes and the curved
part of the rainbow should be in one straight line. This does not usually happen
in mid day, it is either in the morning or afternoon. Morning rainbow forecasts
rain in the West and the Sun in the East, and afternoon rainbow means rain in the
East and the Sun in the West.
Why the sky is red before storm comes?
You must have seen the sky red before any storm comes. What happens at that time,
that before the storm, dust particles fill the lower sky. These particles refract
the lights of the city and the longest wavelength color red spreads out. But this
happens only when the atmosphere is dry. After the rainfall it does not happen so.
How cold is at 10,000 meter height?
You can calculate that how cold it will be at 10,000 meter high place. The formula is:
2 degree C temperature falls at every 300 meter height.
Make any object invisible
When some object does not refract any color of light and absorb it fully then that
object becomes invisible.
Magnet does not attract only iron
You know that magnets attract iron, but do you know that magnet does not attract
only iron? It attracts some other metals too, like aluminum, nickel, cobalt, manganese,
while some metals distract from the magnet like zinc, bismeth etc. Besides, magnet
does not attract very hot iron.
Speed of sound
Why the warm air of Earth becomes cooler on mountains?
In the atmosphere, speed of the sound is 335 meter per second at 0 degree C. But if
temperature rises, then the speed of the sound also rises. Inside water, sound travels
faster. In 8 degree C temperature water, sound travels at the speed of 1435 meter per
second. Thus sound speed depends on the medium in which it travels.
When hot air rises upward, then why the air on mountains is cool? Because
the air becomes warm when it comes into contact with warm earth. So when the
air comes into contact with warm earth and becomes warm, it starts rising.
As it rises, it spreads in a wider area, because air has lower pressure
at higher altitudes. And because of spreading it becomes cooler.