HPS211H1 Lecture Notes - Lecture 4: Electromotive Force, Natural Philosophy, Industrial RevolutionPremium

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5 pages57 viewsWinter 2016

Department
History and Philosophy of Science and Technology
Course Code
HPS211H1
Professor
noahstemeroff
Lecture
4

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HPS211 – 02/03/2016
p. 79-102
The Conservation of Energy
-Industrial Revolution was trying to exploit the forces of nature to power machinery,
looking at machinery and not to produce motive force
-Perpetual motion was a focus of speculation
-Carnot, his son Sadi, productive motive force, focused of the steam engine following the
movements of caloric through the engine, steam was only a way of transporting caloric,
caloric was conserved
-Oersted, interested in natural philosophy, universe should be regarded as a single organic
cosmic entity, convinced there was a link between electricity and magnetism
-Faraday, current-carrying wire rotated around a magnet
-Ampere, surrent-carrying wire that is a helix acts as a regular magnet
-Seebeck, examine connections between electricity, magnetism and heat, produce
magnetic phenomena by heat, a circuit of copper and bismuth where the metals joined, a
current registered
-Grove, correlation of physical forces, no one force could be shown to cause another
because they are all mutually correlative,
-Mayer, heat of tropics bore correlation to oxygenation of blood, heat is motion, calculated
fall of specific weight for the heating of 1º C
-Thomson, used the steam engine to understand nature, centered on work, efficiency and
the elimination of waste, law of thermodynamics: conservation of energy then, absolute
loss of mechanical energy available to man, the perfect engine is the completely
reversible one, argued many things could be defined by energy
-Maxwell, energy at the heart of electromagnetism, electromagnetic energy and ether are
not hypothetical, physics
-Materialism and rationalism
-Helmholtz, denial of perpetual motion, theory applied in mechanical systems, heat
couldn’t be a species of matter because it can be produced out of nothing, conservation of
force
-Clausius, production of heat required flow of heat from one temperature level to another
and the conversion of a certain proportion of the heat into work, heat was simply the
outcome of motion of particles, hot = fast, cold = slow, introduced entropy, rewrote
second law saying entropy tends to increase
-German science was the direct antithesis of British science, looked at mathematics
-Disagreed about the fundamental meaning of what had been discovered and how it fit
into the general scheme of natural philosophy
-Conservation of energy gave room for physics as a discipline
Extra Reading – Online
-Rumford: heat in motion, looked at power of horses and how much they could heat water
-Davy: rubbing ice together, some melted even though the temperature was kept below
freezing, heat is motion
-Faraday demonstrated the relations between magnetism, electricity and light
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-Heat evolved by the combustion of is proportional to its affinity from oxygen, heat
evolved by a voltaic pair is proportional to its electromotive force
-Heat increasing a pound of water 1 degree F, is the force capable of raising 838 lbs 1 foot
-The paddle wheel experiment, on water and on solids
oFriction of water: found the mean increase of temperature due to the friction of
water, 773.64 foot-pounds, equivalent to 1º F
oFriction of mercury: 7.85505 lbs of water, 1 º F
oFriction of mercury type two
oFriction of cast iron: 4.56785 equivalent to 1º in 1.69753 lbs. of water
oFriction of cast iron type two
-The velocity of which the weights struck the ground could be estimated by the noise
-The quantity of heat produced by the friction of bodies is always proportional to the
quantity of force expended
-The quantity of heat capable of increasing the temperature of a pound of water by 1º F
required a mechanical force of a fall of 772 lbs. through the space of one foot
Lecture
Thermodynamic revolution
-promoted a new understanding of the nature of heat, work, and energy
-and the industrial revolution are often discussed together because the invention of the
steam engine initiated the thermodynamic study of the conversion of heat into work and
the law of conservation of energy
Temperature
-17th century – invention of thermometer
-Wasn’t clear what the thermometer measured, what is heat?
-Needed to quantify temperature (fixed point pf heating and boiling point of water)
-No thermometers are the same, fixed points and materials were always changing
-We need to know what heat was to understand how the thermometer worked
Temperature, Heat and Work
-Heat is not a synonym for temperature. A loss of heat might produce a change in
temperature, but heat is a form of energy
-heat was understood as an active principle that can be utilized to produce work
**** Work: applying a force over a distance, the creation of a mechanical change in the
environment, type of energy
Industrial Revolution
-England, 2nd half of the 18 th and beginning of the 19th century
-Creation of a new commercial center (Glasgow, Manchester)
-Scientists were more concerned with control of nature from there commercial centers
-Steam engine is the prominent symbol
Steam Engines
-Born out of the problem of pumping water out of coal mines
-First ones ran on steam, invented in the early 18th century
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