Lecture 11102009

# Lecture 11102009 - Thermodynamics 1st Law of thermodynamics...

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Thermodynamics 1 st Law of thermodynamics is an expression of the principle of conservation of energy Potential Energy – energy due to position or composition Kinetic energy – energy of motion (E = ½ m v ^ 2) Energy Calculation Example Ball A is allowed to fall & strike ball B. Assume that all of ball A’s energy is transferred to ball B at point I and that there is no loss of energy to other sources. PE = mgh (g = 9.81 m/s^2) An amusement park ride starts from a standstill at 102 meters. If all the potential energy of the car, weighting 1000 kg, is converted to kinetic energy before there are any losses, what is the maximum speed that is reached? Answer: 45 m/s PE = (1000) (9.81) (102) = ~ 1000000 PE = KE = ½ m v ^ 2 V = sq.root [(2)( 1,000,000 / m )] Potential Energy Gravitational PE = mgh Electromagnetic Chemical Potential Elastic Potential- putting energy into a spring Nuclear Potential – ability to change a small amount of mass into energy E= mc ^ 2 Kinetic Energy

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Mechanical energy KE = ½ mv^2 Electrical energy- an electron moving through a wire (transfer of energy) Thermal energy- mechanical energy basically (random molecular motion) Sound energy- mass movement, some organized travel Electromagnetic radiation Internal Energy, E or U Internal energy, E or U, is the total energy inside a system (which can be used to do work or be transferred as heat) We can not ever know the absolute value of E But we CAN keep track of the change in E:
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## This note was uploaded on 11/18/2010 for the course CH 301 taught by Professor Fakhreddine/lyon during the Spring '07 term at University of Texas.

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Lecture 11102009 - Thermodynamics 1st Law of thermodynamics...

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