Hooke's LAw
Come on be serious, we want more Hooke's Law!
First of all thanks for all the comments saying you found the site funny. Also, while some have mentioned it helped with home/study work, a few have said there's not actually much Hooke's Law stuff on here. So here is a serious bit about Hooke's Law and what it actually means, as well as a bit about Robert Hooke's life and achievements.
The rough guide to Hooke's Law

Hooke's Law states that "the extension of a helical spring is directly proportional to the weight applied, provided the elastic limit of the spring is not exceeded."

You may also see it written as: "Hooke's Law states that in an elastic material strain is proportional to stress and the point at which a material ceases to obey Hooke's Law is known as its elastic limit."

I prefer the first one, it flows better! :-)

What this means is if you have a helical spring or an elastic material and apply a weight to it it will stretch by a certain amount. If you remove the weight and apply another which is twice as heavy then the spring will stretch twice as far as it did the first time. If you remove that weight and apply a weight that is three times heavier than the first one then the spring will stretch three times further than it did the first time. This is where the "directly proportional to the weight applied" or "strain is proportional to stress" bit is relevant and importantly each time you remove a weight the spring returns to its unstressed size. However this cannot go on forever. There will come a point when the spring is stretched too far and it cannot return to its original state or in fact snaps. At this point the "elastic limit" has been exceeded and Hooke's Law no longer applies.

The Bungie jump analogy on the other page isn't a bad one actually. The elastic rope in Bungie Jumping will stretch by a known amount for someone weighing say 10st (140lbs). Therefore the jump owner will know that if someone comes along who is twice that weight, the elastic is going to stretch twice as much and can decide whether the distance of the drop is big enough or just as importantly whether the elastic limit of the rope would be exceeded causing it to snap. An alternative would be to double up the elastic.

Hooke was a fanatical bungie jumper which is what lead him to Hooke's Law. (Don't put that in your homework as not a lot of people know it). :-)

Who was Robert Hooke?

He was a brilliant scientist, yet for some reason is relatively unknown.

Robert Hooke was born on the 18th July 1635, in Freshwater, on the Isle of Wight. The son of John Hooke, who taught him at home in his early years. Robert soon showed a keen mind, being a quick learner and showing great manual dexterity, making mechanical toys when he was a boy. He went to Westminster School when he was thirteen, and from there on to Oxford where he would meet many of the great scientists of the day. There he impressed with his abilities in constructing equipment and designing experiments and in 1658 he became assistant to Robert Boyle. He was friends with, worked with and sometimes argued with many scientists of note such as Christian Huygens, Christopher Wren, Robert Boyle, Antony van Leeuwenhoek and Isaac Newton. Regarding arguing Hooke and Newton had a somewhat tempestuous working relationship culminating in a bust up regarding their views on gravity. In 1662 Hooke was named Curator of Experiments of the Royal Society of London. He died in London on March 3, 1703.

His own field of study was wide, spanning physics, biology, chemistry, astronomy, architecture, geology, engineering and more. One review of Hooke says that given his wide ranging interests he perhaps spread himself too thinly, the suggestion being that he was a Jack of all trades but master of none. That is grossly unfair given his knowledge and abilities in each sector and his achievements...

Robert Hooke's other discoveries and inventions

Robert Hooke was the first to coin the phrase "cell" in biological terms. In his written work Micrographia, he wrote:

. . . I could exceedingly plainly perceive it to be all perforated and porous, much like a Honey-comb, but that the pores of it were not regular. . . . these pores, or cells, . . . were indeed the first microscopical pores I ever saw, and perhaps, that were ever seen, for I had not met with any Writer or Person, that had made any mention of them before this. . .

Micrographia was published in 1665. It is based on Hooke's observations of the world (and beyond) using magnifying lenses. In it he makes observations and discoveries both minute and astronomical. The stunning illustrations in the book were drawn by Hooke himself. Below are examples of a flea and of the cells mentioned previously. In the book the image of the flea was 45cm across. Add artist to his list of talents. The importance of Micrographia cannot be understated. Up until its release the microscopic world was virtually unknown. In this work it came to life and its effect was profound, opening up avenues for other scientists.

Micrographia fleaMicrographia cell

Hooke also invented the iris diaphragm for cameras, a universal joint used in motor vehicles, the balance wheel in watches and a wheel barometer. He discovered spots on Jupiter and was probably the first to explain what fossils were. Although untrained he was a great architect and was given the position of Surveyor by City of London officials following the Great Fire in 1666. Wren was given the appointment of Surveyor to the King and together they designed most of the Royal and City buildings. Sadly none but one of Hooke's designs remain today, which is possibly why Hooke is little known as an architect.

There is much more to Robert Hooke's fascinating life than is covered here.
A chronological list of his career achievements can be found here and a detailed biography here.

Other Hooke links

England's Leonardo


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