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Come
on be serious, we want more Hooke's Law!
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| 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. |
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The
rough guide to Hooke's Law
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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). :-)
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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...
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Robert
Hooke's other discoveries and inventions
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Robert
Hooke was the first to coin the phrase "cell"
in biological terms. In his written work Micrographia,
he wrote:
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. . 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.
 
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.
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