Thermaldynamics

Thermaldynamics - Exam 1 Bead on a wire The accelerations...

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Exam 1

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Bead on a wire The accelerations at D (A) are in the +y (-y) directions. The speeds are the same but the directions are different. At b, there is more potential energy, less kinetic, so the speed has to be less.
Temperature The quantity that indicates how warm or cold an object is compared to some standard is called temperature We use a device graduated in a scale to measure the temperature a thermometer works by means of expansion or contraction of a liquid, usually mercury or colored alcohol The most common temperature scale in the world is the Celcius (also called Centrigrade) scale named after Anders Celcius 100 degrees between the freezing point of water and its boiling point But in the United States, the Farenheit scale is more common, named after the German physicist Farenheit in this scale, water freezes at 32 degrees and boils at 212 degrees 0 o is the temperature of the coldest salt water solution in official use only in the US and in Belize

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Conversions Temperature (C) = 5/9 X ( temperature (F) -32 o) The two are equal at -40 o , cold no matter what scale you use to quote it
Temperature and heat Temperature is proportional to the average kinetic energy per particle in a substance how fast the atoms are moving in a gas or liquid or how fast the atoms are vibrating in a solid Thermal energy refers to the sum of the kinetic energy of all particles in a substance If I take a cup of hot water and pour out half of it, the temperature of the remaining half is still the same, but the thermal energy has been cut in half When we measure the temperature of a object, thermal energy flows between the thermometer and the object Eventually the thermometer and the object come to thermal equilibrium same average kinetic energy per particle

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States of matter As the temperature of an object increases, a solid object will melt and become a liquid; with more heat input the liquid will vaporize and become a gas As the temperature is increased further, molecules dissociate into atoms and atoms lose some or all or their electrons, thereby forming a cloud of electrically charged particles, or a plasma Plasmas exist in stars, where the temperatures can reach millions of degrees There is no upper limit on temperature Four states of matter solid liquid gas plasma
Absolute zero In the 19th century, physicists found something amazing Suppose you start with a gas at 0 o C The volume decreases by a fraction 1/273 for every degree decrease in temperature This implied that if a gas were cooled to -273 o C, it would decrease to zero volume of course, by this point the gas would have turned into a

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Thermaldynamics - Exam 1 Bead on a wire The accelerations...

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