Ever wondered what friction actually is? If so then don’t worry you’re not alone, I've often questioned what the actual mechanics behind the force are, and I’ve come up with an answer.
As we’re all told in primary school, friction is the force that acts on two objects when they contact one another. The question is just what is this force?
Well every object is made up of molecules, which are made up of atoms. When two objects touch one another the molecules in the objects form relatively weak electrostatic intermolecular bonds (weak compared to intramollecular bonds such as ionic or covalent bonds) with one another. It is these attractions that need to be broken when two objects move apart or slide over each other.
Now although the attractions are weak they still exist and in great numbers, so some energy needs to be used to break the attractions. This is where the term friction really comes into being. To break the bonds, say between your two hands when they’re pressed palms together, you need to apply kinetic (movement) energy to break all the tiny attractions between the surface molecules of one hand and the molecules of the other, to do this you may apply a rubbing motion.
When you break bonds the bonds need to absorb energy to do so, this is known as being endothermic (A process that absorbs energy from its surroundings). So when you rub your hands together the action of you rubbing your hands provides the energy to break the bonds, and this kinetic energy is transferred to the bonding molecules on the surface of your hands, breaking their bonds with one another and in the process transferring some of the kinetic energy to them, making them more energetic.
This energy means that the molecules that make up the surface of your hands bump into each other more and the kinetic energy becomes thermal (heat) energy, and this is why your hands heat up when you rub them together. The same thermal increase happens when ever friction arises between two moving surfaces.
So in summary, friction is the force that needs to be applied to overcome the electrostatic intermolecular bonds that form between two objects in contact, i think.
I was reading through one of the my A-level chemistry book when I came across an estimate that they had recorded for the total volume of the sea, which they worked out to be 1.37x109Km3 or 1370000000Km3 and this intrigued me somewhat, so I had a rummage through the internet to see if I could find an estimate for the average density of saline water, which I found I think on yahoo answers (Not exactly a solid peer reviewed source) and thought I’d do some calculations. Here’s what I came up with.
Estimated Volume of the sea = 1.37x109Km3
Average density of saline water = 1027Kgm-3
1.37x109Km3 = 1000000000(1.37x109m3)
= 1.37x1018m3
Mass = 1027Kgm-3(1.37x1018m-3)
= 1.40699x1021Kg = 1.40699x1018tonnes
= 1,406,990,000,000,000,000 tonnes
This number is 1.4 Quintillion tonnes.
Of course this figure is extremely rough with error bounds probably somewhere in the trillions of tonnes thanks to soluble debris from river and human activities, but still it gives you an idea of just how huge the oceans are.
Sources
Volume of Ocean from Salters Advanced Chemistry’s Chemical Storylines A2, Third Edition, published by Heinemann books, page 126
Average Density of Sea Water taken from a discussion on Yahoo answers but later found on website http://hypertextbook.com/facts/2002/EdwardLaValley.shtml data recorded by several reputable sources.
Upon a whim I decided to construct a list of the 20th century’s most influential figures. Originally I wanted to make it a top ten, but I just couldn’t fit everyone I wanted on, so decided to make it a top 15.
15. Bill Gates – Founder of Microsoft along with Paul Allen and lead software architect, William Henry Gates the third’s company has almost monopolised the home computing market for over a decade.
14. Richard and Maurice Macdonald – Whether you love or hate the fast food giant, McDonalds has been visited by almost everyone, and you have these two brothers to thank for that, with their kitchen to customer in 10 seconds policy (waiting times have certainly changed since its founding)
13. William Wadsworth Hodkinson – ‘The man who invented Hollywood’ everyone who enjoys the products of the film industry has this man to thank for his revolutions in the way that films were made and distributed.
12. Scott Joplin – The most prominent ragtime musician, his music was the precursor to Jazz and so ultimately the grandfather of almost all modern music.
11. Leo Hendrik Baekeland – Accidental discoverer of Bakelite, the world’s first thermoset plastic. Considered a useful material for design and manufacture Bakelite replaced woods and metals due to its light an durable properties..
10. Sir Frank Whittle – Inventor and first person to patent the design of a jet engine (1932), he was however beaten into producing a working model by Hans Von Ohain working independently in Germany.
9. Werner Von Braun – A one-time member of the Nazi party and lead designer for the American space program, Von Braun designed the first ballistic missile (V2) for Nazi Germany before being taken to the US by the American government to work on the US Inter Range Ballistic Missile program. He also developed the Saturn V launch vehicle which propelled the Apollo space craft to the moon, giving the US the edge against the soviets in the space race.
8. Julius Robert Oppenheimer – Leader of the Manhattan project, and father of the bomb. On seeing the detonation at trinity Oppenheimer recalled the Hindu scripture Bhagavad-Gita Gita saying "If the radiance of a thousand suns were to burst at once into the sky, that would be like the splendor of the mighty one... Now, I am become Death, the destroyer of worlds."
7. Fritz Haber – Developer of the Haber process by which ammonia is produced continuously on mass, essential for the production of fertilisers and explosives.
6. Howard Florey – Developed a technique by which penicillin could be mass produced, Florey’s work was vital in saving the lives of many soldiers during the Second World War.
5. Nikola Tesla – The Serbian born American electrical engineer Tesla developed the alternating current system, outselling Thomas Edison’s direct current in the war of currents, the system we still use to this day to power all the electrical items we consider ‘essential’.
4. Albert Einstein – Arguably the greatest physicist that ever lived and also the greatest mind of the 20th century, Einstein’s development of particle physics was revolutionary the subject, from his work on Brownian motion, to his theory of relativity, he also helped set the stage for the development of the bomb. Escaping Nazi Germany while he could, Einstein was offered the presidency of the newly formed state of Israel but declined in 1952 saying "Politics is for the moment, equation for the eternity."
3. Henry Ford – Founder of Ford and designer of the model T, Henry ford was instrumental in conception of ideas of continuous manufacture, mass production and fairer wages for staff. He brought a lot of foreign money into the US economy and made sure that his workers were able to spend that money on the products they produced, increasing the spending power of the working class.
2. Karl Marx – Creator of the Marxist philosophy and ultimately the father of communism, a mantra that created a conflict that lasted almost 50 years, and can still be felt in places like China and probably the last bastion of true communism, North Korea. Communism propelled Russia onto the main stage for most of the 20th century, was the reason many cultural revolutions which still have power today and had the world hold its breath (metaphorically speaking thank god) for half a century.
1. Adolph Hitler – The archetypal tyrannical dictator, Hitler was driven by a blind hatred of people who differed from his ideal, going to the extent of murdering over 6 million Jews and millions of others who were considered unclean or opposed him. However If you ignore the extreme levels of insanity that he possessed, and also induced in the people around him, Adolph Hitler actually accomplished a lot during his reign of terror. He managed to grasp total power from the weak German government, and also managed to quell dissent within his own party, all through questionable means of course. He also managed to bring Germany back from the brink of economic collapse and significantly improve its infrastructure. He also managed to rearm Germany and advance its military technology in relative secrecy. Under his authority the world’s first ballistic missiles, jet engines and first assault rifles were created and put into use (in fact it often occurs to me how lucky we can count ourselves that the former two came too late to really change the tide of the war). He was also a brilliant speaker, managing to cast a spell of nationalistic speeches that enslaved the minds of an entire nation. Ultimately he was the man that started the largest war that the planet has ever seen, a war that changed all war, and a war that really showed what man was capable of doing to one another, and a war that had it gone differently would have changed the map indefinitely. He untied allies that had otherwise totally conflicting political dogmas. It is all these legacies that affected so many people directly, in so many different ways that will be retold, repeated and analysed for generations that make him the most influential man of the 20th century.
