How do icebergs form?

Icebergs are blocks of fresh-water ice that break off from glaciers and float out to sea. Glaciers are formed in polar regions where snowfall lasts for centuries, or even millennia, without entirely melting, and is eventually compressed into ice.
In the North Altantic, most icebergs originate from the tidewater glaciers of Western Greenland. Compressed snow becomes firm, a granular snow, transformed eventually by pressure into a dense ice. The weight of the icecap builds, causing the ice to flow as much as 60 feet a day through openings in the coastal mountains. Rising and falling tides cause slabs of ice to break off and form moving "rivers of ice".


How does scratching cure itching sensation?

Very sensitive, rapidly adapting, mechanoreceptive free nerve endings that elicit only the tickle and itch sensation are found almost exclusively in the superficial layers of the skin. This sensation is transmitted by very small type - C nerve fibres. These nerve fibres are unmyelinated fibers with a diameter of 0.5 to 2 microns. These fibres transmit impulses as slowly as 0.5 m/sec, unlike the type - A fibres, which transmit impulses at velocities as great as 120 m/sec.
The process of scratching can relieve itch. This scratch reflex is the important spinal cord reflex found in some animals including man. This reflex is initiated by the itch and tickle sensation. It involves two different functions (1) a position sense that allows the hand to find the exact point of irritation on the surface of the body and (2) a to and fro scratching movement. This scratching removes the irritant and the itch is relieved. Sometimes the scratch is strong enough to elicit pain. The pain signals are believed to suppress the itch signals in the cord by the process of lateral inhibition. This lateral inhibition is by the transmission of sensory signals by the anterolateral system, in contrast to the dorsal column system. The anterolateral system is a cruder type of transmission system than the dorsal column system.


What is meant by ozonised mineral water?

Ozone is a blue gas with a relative molar mass of 48 and molecular formula of O{-3}.
It converts back into oxygen after its oxidising process. This makes it the most eco-friendly treatment known today.
Ozone is the ultimate in disinfection. When drinking water is treated with chlorine (chlorine is a highly carcinogenic chemical), the residual chlorine in water is also consumed along with the water.
On the other hand ozone, having half the life of only about 20 minutes, unreacted ozone reduces to oxygen, leaving no trace of toxicity in water.
The water is free from chlorine. Ozone reacts with impurities such as micro organisms including bacteria, virus, spores, mould and fungi. Chemicals such as chlorine neutralise them.
As ozone destroys all micro organisms and it removes disagreeable odours, the resultant water is absolutely safe, pure, fresh and healthy. Ozonised water is colourless and odourless.
The advantage of the use of ozone in water is that it does not leave a dangerous chemical residue like many conventional treating chemicals.
Ozone generators produce ozone by passing oxygen through an electrical field.
Then the generated ozone is bubbled through the water to be treated in a specially designed vessel to control rate of injection. The amount of ozone to diffuse in water depends on the contamination of water.


What is the difference between dial up and broadband Internet connections?

The fundamental difference between dialup and broadband connections is the manner in which the connection is made from PC to the Internet.
A dialup service connects to the Internet through a phone line with a maximum speed of 56kbps.
Broadband refers to a connection that has capacity to transmit large amount of data at high speed. Presently a connection having download speeds of 256kbps or more is classified as broadband.
Broadband comes in a number of forms - depending how the data is delivered - for example via cable, satellite and most commonly using a telephone line where as a dialup service always connects to the Internet through a phone line.
While using a dialup connection, we need to pay for a local call every time we dial the Internet. In addition phone line is engaged while we are on the Internet. With a broadband connection, phone line (if existing phone line is used) can still be used while using the Internet and both the phone and the Internet work simultaneously and no dialup costs are incurred. Telecommunication systems were originally built to carry analogue signals. In a dial up connection, modems are used to translate digital into analogue signals and communicating with Internet.
However, analogue transmission between the subcriber and the telephone company is a bandwidth bottleneck. Dialup connection speeds make it more difficult to view certain types of media, such as video, and it can take much longer to download and open emial attachments, play online games and so on.
In an broadband system, digital data does not have to be converted into analogue. it uses a different part of the line's frequency spectrum, offers much wider bandwidth 9more lanes) and does not interfere with the use of the line for voice transmission. When connected to the Internet, such a connection allows surfing or downloading much faster than a dial-up connection. Dialup connection users a built-in modem to connect and does not require a special router, whereas broadband requires a special router or modem.
In terms of security for attack, dialup is more secured then broadband, Broadband users need to use a firewall to keep the computer "invisible" to the outside.


Why do eggs become hard on boiling?

Egg contain 67 per cent proteins (in egg white) and 33 per cent fats and proteins (in egg yolk). Egg white protein is mostly albumin (ovalbumin and Conalbumin) All proteins have primary,secondary and tertiary structures.
Tertiary structure of egg white protein is due to hydrophobic interactions and hydrogen bonding. They also contain Cysteine amino acid, which has sulfhydryl group (SH).
These sulfhydryl groups form covalent disulfide bonds and hold 2 distant sections of proteins in close proximity. Disruption of the tertiary structure (or 3 dimensional structure) due to heat, chemicals or acidity is called "denaturation".
When we heat an egg, the, heat breaks the intermolecular forces and the tertiary structure gets broken. The proteins unfold from their nature folded structure and precipitate forming a white solid mass.

Why is standing in boats or double decker buses not allowed, particularly in the upper deck of buses?
On tilting the centre of gravity of the boat or bus is lowered and it is likely to overturn.

When wood burns it crackles. Explain?
Wood contains a complex mixture of gases and tar forming vapors trapped under its surface. These gases and tar vapors escape, making a cracking sound.

Why do stars twinkle?
The light from a star reaches us after refraction as it passes through various layers of air. When the light passes through the earth?s atmosphere, it is made to flicker by the hot and cold ripples of air and it appears as if the stars are twinkling.

Why is it easier to roll a barrel than to pull it?
Because the rolling force of friction is less than the dynamic force of sliding friction.

Why is it recommended to add salt to water while boiling, in cooking?
By addition of salt, the boiled point of water gets raised which helps in cooking sooner.

Why is it the boiling point of sea water more than that of pure water?
Sea water contains salt, and other impurities which cause an elevation in its boiling point.

Why is it easier to spray water to which soap is added?
Addition of soap decreases the surface tension of water. The energy for spraying is directly proportional to surface tension.

Which is more elastic, rubber or steel?
Steel is more elastic for the same stress produced compared with rubber.

Why Does ink leak out of partially filled pen when taken to a higher altitude?
As we go up, the pressure and density of air goes on decreasing. A Partially filled pen leaks when taken to a higher altitude because the pressure of air acting on the ink inside the tube of the pen is greater than the pressure of the air outside.

On the moon, will the weight of a man be less or more than his weight on the earth?
The gravity of the moon is one-sixth that of the earth; hence the weight of a person on the surface of the moon will be one-sixth of his actual weight on earth.

Why does a solid chunk of iron sink in water but float in mercury?
Because the density of iron is more than that of water bus less than that of mercury.

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"Life is either a daring adventure or nothing."
Helen Keller