Gas in India has various meanings. You could get ‘gas’ by visiting a Gujarati wedding and gorging on dhokalas, undius and misals. The silent version of this ‘gas’ invariably makes others around you crinkle their noses in disgust. The noisy version is likely to leave you embarrassed and a butt of jokes in many future occasions.

Gas in India is also a common term for cooking gas or LPG.  It’s fairly common to see the ‘gaswallas’ cycling the blood-red cylinders around the city to supply gas. Because there are so many confusing meanings for gas in India, we prefer to call the car fuel petrol.

Gas, in ‘Amrica’, my friend, is short for Gasoline. Americans have a way of ‘Americanizing’ things… this term is a result of such creativity. The word “gasolene” was coined in 1865 from the word gas and the chemical suffix -ine/-ene. The modern spelling was first used in 1871. The shortened form “gas” was first recorded in American English in 1905. Gasoline originally referred to any liquid used as the fuel for a gasoline-powered engine, other than diesel fuel or liquefied gas; methanol racing fuel would have been classed as a type of gasoline.

The word “petrol” was first used in reference to the refined substance as early as 1892 (it was previously used to refer to unrefined petroleum), and was registered as a trade name by British wholesaler Carless, Capel & Leonard.

Most Commonwealth countries or former Commonwealth countries, with the exception of Canada, use the term “petrol” (abbreviated from petroleum spirit). The term “gasoline” is commonly used in North America where it is often shortened in colloquial usage to “gas”. This should be distinguished in usage from genuinely gaseous fuels used in internal combustion engines such as liquefied petroleum gas (which is stored pressurised as a liquid but is allowed to return naturally to a gaseous state before combustion).

Have you heard the word mogas? Its short for motor gasoline and distinguishes automobile fuel from aviation gasoline, or avgas. The word “gasoline” can also be used in British English to refer to a different petroleum derivative historically used in lamps; however, this use is now uncommon.

That’s enough on gas for now. Uff… What’s that smell??

Since you have specified yourself as the test specimen in this experiment, we’ll start by throwing you in the ocean. Then we’ll figure out a way to measure the water above your head. Scrap idea. Note to self: Curiosity kills, but not literally.

The weight of water per cubic feet is 28.316847kg

- The density of fresh water is  62.4 pounds per cubic foot (28.3 kg/ 0.03 m³).

- Seawater, however, is denser: 64 pounds per cubic foot (29 kg/0.03 m³).

Since you have chosen the ocean to immerse yourself, I am going to consider seawater weight for our calculations.

Usually, a person’s weight is slightly less than the weight of the displaced amount of water. For example, a person who weighs 80kg displaces 79dm2 of water, which weighs 79kg, that is, he has about 1kg of negative buoyancy. So considering you displace 79kg of water when you are just immersed, at 100 feet you will displace around the same amount of water. But this again changes with your level of buoyancy which depends on the amount of air in your lungs

Here’s the part where you start reading slowly because the sentences are strung together with little complex words.

Now, if we define pressure as weight per unit area, the force exerted on a body immersed in a liquid is due to the weight of the liquid above the point where the pressure is being determined. Therefore the pressure of a liquid is directly proportional to its depth and the liquid exerts the same amount of pressure in all directions.

We take some good looking equations here to prove the point. Non-physics, non-maths and general ‘non’ people can skip to the answer which is 44.44ibf/in-sq.

For others:

Pressure = weight / area

Volume is the cross sectional area x height. Substituting this above,

P = phg / g1

Therefore, if the density of water is 64 lbm/ft-cube, and at a depth of 100ft,

=(64 lbm/ft-cube)x (100ft)x(32.17ft/sec-sq / 32.17lbm-ft/lbf-sec-sq)

=(6400 lbf/ft-sq) x (1 ft-sq / 144 in-sq)

= 44.44 lbf/in-sq.

If your are going ‘huh?’ at the end of the equation, I’ll make it simple. It’s a lot of pressure / weight at 100 feet and you don’t want to be there unless you can bet on discovering a hidden treasure.

All pressure and no brain makes you a dull boy. So how about you tell me how the china and other fragile items from shipwrecks remain intact for several years despite the pressure on the bottom of the ocean?

At this point, realization would ideally dawn that CK not only has good answers but also good questions. Read on.

Solids do not have air pockets in them to be effected by external pressure. Therefore, things like fragile china only get slightly smaller when equal pressure is applied on all sides. But for substances like wood, which is porous, you can forget you’ll ever recognize a sunken chest.

Free-diving, or apnea traces its 4,500-year-old roots to pearl diving and Mediterranean deep-sea fishing. Deep diving without equipment is not such a bright idea. Although people can get to surprising depths, their dives are limited to their individual capability and only last a minute or so.

Apnea of more than approximately one minute’s duration leads to severe lack of oxygen in the blood circulation. Permanent brain damage can occur after as little as three minutes and death will inevitably ensue after a few more minutes unless ventilation is restored. The most common danger is of a blackout, which occurs when the diver pushes to a limit where the oxygen drops to a level that the brain can no longer perform normal functions and the diver passes out.

But it’s a whole different world for record divers. The current official world record (October 2007) for Constant weight apnea without fins (an AIDA* free-diving discipline in which the free-diver descends and ascends swimming without the use of fins or without pulling on the rope or changing his ballast;) is held by William Trubridge of New Zealand for -82 meters! The same record in the women’s category is held by Natalia Molchanova of Russia at -55 meters. (*Courtesy AIDA International, Association Internationale Pour Le Developpment De L’Apnee, the world’s largest federation for breath-hold diving)

How does one decide what sunscreen to buy? I thought the higher the number on the SPF, the better the protection!! Invariably I would look to buy a sunscreen that has the highest SPF number. But why would anyone buy a bottle that has a lower SPF?

Does SPF 15 mean there are 15 layers of shields around you. It’s as if there is an invisible shield around you protecting you from the harmful effects of the sun’s rays. Is it like the way the show in comic books? The way superheroes throw an invisible shield around themselves to protect them from evil weapons.

I decided to then get to the bottom of the matter. We all know that SPF means Sun Protection Factor. But what do the numbers really mean. Franz Greiter is credited with introducing the concept of Sun Protection Factor (SPF) in 1962, which has become a worldwide standard for measuring the effectiveness of sunscreen when applied at an even rate of 2 milligrams per square centimeter (mg/cm²). Hmm….. I never really measured the quantity of sun screen that ive applied per square cm of my face!

What SPF really means is the amount of time a person can be exposed to sunlight before getting sun burnt. If a person’s skin burns after 10 minutes in the sun, with a sunscreen of SPF 15, he would burn after 150 minutes in the sun. ie. 10 x 15 = 150 minutes.

SPF isn’t really the number of shields that it throws around you, but it indicates how long the cream can protect you against the sun’s rays. A standard rule of thumb that can be used is to multiply the SPF number by 10 and use that as a reference point. This also depends on the type of climate you live in. Very humid conditions where you sweat a lot may wear off the sunscreen quickly and you may have to constantly re apply. Newer sunscreens have been developed with the ability to withstand contact with water and sweat.

So, the next time you buy a sunscreen, do take into consideration the climate (dry/humid), how long you’ll be out in the sun, the number of times you need to reapply and make sure you know your multiplication.

If cabin pressure wasn’t required, you could have a good open-window view during flights and people would fight for window seats! (not that they don’t do it now, it’ll just be more). You could, literally, keep your head among the clouds! What if someone decided to open a window and jump? Oh… what if someone takes their very bad habit of spitting or littering and throw things out…eeks…!!! Ok… slow down there Imagination… all that’s not happening.

Cabin pressure is not for the above mentioned reasons but it works for them too.

When you are around 8,000 ft above sea level, there is about 25% less oxygen. Most people can tolerate the difference without ill effects. If you have heart disease though, you might experience symptoms of hypoxia (shortage of oxygen in the body) even as low as 5,000 ft. As the altitude increases, one might become sluggish or experience unconsciousness.

Aircrafts that fly regularly above 10,000 ft are equipped with an oxygen system. Cabin pressure is maintained by

a)      Using masks or canulas, typically in a smaller aircraft

b)      Using an ECS or an Environment control system. This system uses “bleed air” in which the air extracted from the engine is compressively heated at 200 degrees C and then cooled by passing through a heat exchanger.

Most aircrafts also have a manual back-up system and these systems maintain pressure equivalent to 8000ft or lower even at altitudes above 43000 ft. So what you breath in modern airlines is 50% “outside air” (from the compressed air system) and 50% “filtered air” (from the recirculation fans). There is some truth when they say that the air in the first class is better! Most jetliners supply constant flow per unit length of the cabin. The seats in first class are spaced farther apart, resulting in more air per seat, but the nozzles provide the same amount of air at all locations.

If you are wondering about the queasy feeling and blocked ear (called “aerotitus”) during flights, your answer is here. When an airplane compresses and decompresses, the gases in your body may expand or contract in response. Also, that’s why you have oxygen masks flying down in the event of a pressurization failure.

Now you know why people start flying all over the place when they show a villain firing a hole inside the aircraft. The pressure inside the airplane might be 70 kPa (10 psi), while the pressure outside is only 15 kPa (2 psi). An otherwise-harmless pinhole under these pressure differences will generate a high-pitched squeal as the air leaks out at supersonic speeds. Quite an apt situation to pray to all the Gods you know and even the ones you don’t.

If you haven’t seen a bat do this, be paitent and keep observing
(i.e. if you don’t want to believe us and have nothing better to do).

However, the recorded Hottest Place in the World is El Azizia, Libya, which, in 1922 recorded an amazing, blazing 157° F/ 57.8°C! 

How hot is hot you ask? Well, there are plenty of hotter places around the world (like where Brad Pitt lives) but it is important to note that when atmospheric temperatures are recorded it is not the surface temperature, where it can sometimes reach 150° F/ 66° C, but rather the air temperature at about 5 feet (1.6 m) above the surface in an enclosed shelter. Since hardly any humans reside under these conditions you won’t find any meterological stations to record these extreme temperatures. 

Did you know that two-thirds of the Earth Surface is covered in water from the oceans but a third is dry desert! But that still does not stop my grandmother from yelling “Don’t run the shower for too long!”

All deserts are not hot (but all green-eyed, dark haired hunks are), Antartica, for example is coldest, driest desert on Earth, since the lack of precipitation – less than 10 in/25.4cm per year is what defines a desert! 

 The coldest place in the world has got to be my in-laws home! Boy, I shiver, no matter what, every time I visit!  

But, as my erudite friends corrected me- the coldest place in the world is Antartica, which besides being the Land of Extremes/The World’s Biggest Laboratory is the windiest and highest continent on Mama Earth! The Coldest reported temperature ever was -89.4°C/-129°F.

Because Antartica is covered in ice (which has been there forever) and yet receives very little rainful, it is the largest desert on Earth. Did you know that 90% of the ice on earth is located in Antarctica and I thought it was my mother-in-law’s refrigerator! 

It is no wonder then, that due to its extreme and inclement weather Antartica is the only continent that has never had an indigenous population of humans! Imagine the peace it enjoys! Antartica belongs to the free world hence the exploration of this unique place has been shared by countries all over the world (my in-laws would surely love it there!).  

Amazing factoid! During winter Antartica has no sun and hence the cold becomes unbearably bone-chilling with no daylight whatsoever! Almost like living in space. Now, I know what to gift my in-laws this coming Christmas!Psst…my father-in-law informs me that the coldest city on Earth is the city of Yakutsk, Siberia. Maybe he would rather go there instead!

Incidentally the wettest place on Earth (besides my son’s classroom on Open Day) is Cherrapunji, India!

Strangely, one of the driest places in the world, The Atacama desert is nestled along the coast of Chile, South America – right next to the Pacific Ocean which is  the biggest body of water in the world!  

Currency was basically created to serve as a medium of exchange. In the initial days, metals were used to represent stored value and symbols on them were used to represent commodities. This system had obvious flaws. There was no safe way to store the currency, therefore, it could be only as sound as the people who defended it. Basically, if you had a knife, you could make an offer no one could refuse. So a safe treaty was established for merchants, but it is now known exactly what was used as exchange. This system came to an end because of piracy.

Then, during coinage, metals like gold and silver were mined, weighed, and stamped to assure the individual taking the coin that he was getting a certain known weight of precious metal. Our dear own Archimedes helped here in solving the counterfeit problem by helping test the fine weight of metal even if it had been tampered with.

But the system had its problems. It became cumbersome exchanging thousands of coins. (imagine being Richard Branson or Bill Gates in that era, life would be so difficult managing vaults and vaults and vaults of money… not that they don’t do it now secretly.. ahem.. we won’t go there now). This resulted in the creation of paper money, commonly known today as bank notes. First, the mings and chings of China monopolized over issuing paper money. It was not until the mid 13th century that a standard and uniform government issue of paper money was made into an acceptable nationwide currency.

Now, the problem was that, during that era was that one could be the James Bond of finance and literally have the ‘license to print money.’ Which led to having more money than commodities. (Imagine having unlimited money and limited commodities. Prices would rise so that only people who could pay more would buy – That’s what we call ‘Inflation’). Imagine having a balloon. You could blow only x amount of air in it. If you inflate the balloon more than its capacity, it would burst.

The solution began evolving in the late 18th century with the creation of a central money authority with the monopoly on issuing currency. There were hitches in this system too, but they were slowly resolved with most of the industrializing nations on some form of gold standard, with paper notes constituting the circulating medium.

Disclaimer: Intellectuals please continue reading, for the lesser mortals, you can suffice by knowing that prices will continue to rise and you will always fantasize that when you were younger things were cheaper, politicians were nicer and the world was a better place.

Now, where were we… ah…value of money today. Things get a little complex with the term ‘exchange rate’. This says that ‘A currency’s value is determined based on its comparison with another currency.’ For example, if one bag of potatoes cost Rs.10 in India and 50 cents in US, then it is concluded that Rs.10 is equal to 50 cents. This is called purchasing power parity (PPP) by the people in the business.

There can be two scenarios: The exchange rate can be fixed or floating.Exchange rates between two countries can be fixed based on a monitory policy they maintain. If it’s floating, ‘international market forces’ (I don’t mean the CIA by that) decide the rate based on various factors.

Typically, a currency rate is determined by multiple factors like economic growth, strength of the economy, inflation rate and demand for the currency. If more people buy the currency, the currency becomes stronger and vice-versa. For example, if there are large inflows of foreign money into India, and that money gets converted into rupees, it increases the rupee value.

Inflation (the term is to refer the unlimited money and limited commodity problem earlier) will also play a role in determining the value of the currency. For example, if the inflation rate in India is expected to be 5% in the next 12 months and 2% in the US for the same period, potatoes might cost Rs.10.50ps in India next year, while they would cost 51 cents in the US. In other words, the rupee would have depreciated against the dollar.

There’s more gyan on free floating currency and movable or adjustable peg system of fixed exchange rates. Sweets, I have enough complex information to write a book on this, and since this borders on basic gyan, I’m going to stop here. As for the potatoes, go easy on them.

Full cream, or whole milk, has the full milk fat content. For skimmed or semi-skimmed milk, all of the fat content is removed and then some (in the case of semi-skimmed milk) is returned. The best-selling variety of milk is semi-skimmed; in some countries full-cream (whole) milk is generally seen as less healthy and skimmed milk is often thought to lack taste.

Whole milk is about 4% fat. Semi skimmed milk is about 2% fat. Skimmed milk is about 1% fat. Fat in diluted milk depends on the % of dilution.

Let me start by saying, constant knuckle cracking can make you look like a social hazard in a sane environment, so a good tip is to lose the habit.

There are quite a few theories on the story behind the sound. These include:

a) Broken adhesions: As two cartilage surfaces are pressed together, they form adhesions, and when the joints are separated this makes the popping or cracking sound.

b) Rapid stretching of ligaments.

c) Cavitation (The most popular one): Knuckles are surrounded by Synovial fluid (the fluid has about 15% carbon dioxide). When you crack your knuckles or tug on your fingers or toes, a low-pressure zone is created in the synovial fluid which draws CO2 and water vapour out of the solution creating an air bubble which collapses almost instantly, causing the popping sound.

Once the big gas bubble has popped, a little one remains behind for about 15 or 20 minutes before the CO2 inside it is totally redissolved. During that time, any further finger-tugging simply causes the micro-bubble to expand a bit, like a tiny shock absorber. That’s why you can’t crack the same knuckle twice in rapid succession.

There is a hypothesis that prolonged joint stress due to cracking knuckles may eventually lead to a higher risk of joint damage. This is not proven yet and if you continue your habit, the world might have the privilege to see the first victim of knuckle cracking damage and parents could continue to say ‘I told you not to do that.’

Movie magic: An unnaturally loud knuckle cracking before a Hindi movie fight scene shows off the hero’s (or villain’s) power and preparedness!