E&S: Lecture 1

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  1. What is energy?
    • -scalar quanity, related to the energy content of a system, no direction
    • -movement
    • -capable of accomplishing work
    • -conserved
    • -SI system: Joules (J)
  2. Force
    • -Act at a distance and cause bodies to accelerate
    • -Units: kg m sec^-2
    • F =ma
  3. 4 forces
    • 1. Gravitational
    • 2. Electromagnetic
    • 3. Strong nuclear
    • 4. Weak nuclear
  4. Work
    • -Force integrated over distance
    • -lifting things, smashing things takes work
    • -Units: Joules (J)
    • W=Fd
  5. Kinetic energy
    • -energy associated with moving objects
    • KE= 1/2mv^2
  6. Photon energy
    • -Massless bundles of electromagnetic energy
    • -Electromagnetic radiation cam be described as electromagnetic waves or particles
  7. Equation: Energy of photons
  8. Heat energy
    - kinetic energy associated with the random motions of atoms and molecules
  9. why can potential energy be stored within systems?
    Their physical configuration
  10. How can you increase the potential energy of a system?
    By doing work againts a conservative force field
  11. Potential energy is ______not _____
    Potential energy is relative, not absolute
  12. Potential energy can be converted to ______
    • other forms of energy
    • ex. kinetic energy and heat
  13. Alteration: Gravitational Potential Energy
    Altered by doing work against a gravitational field
  14. Alteration: Elastic Potential Energy
    Altered by doing work against an elastic material
  15. Alteration: Electrostatic Potential Energy
    Altered by doing work against an electrostatic field
  16. Alteration: Magnetic Potential Energy
    Atered by doing work against a magnetic field
  17. Alteration: Chemical Potential Energy
    Altered by forming and breaking chemical bonds
  18. Friction
    non-conservative force that resists motion
  19. Work done gaints frictional forces
    • -does not store potentiale energy
    • -dissipated as heat
  20. Power
    • -A scalar quantity related to the rate of energy gain/loss of a system per unit of time
    • Unit: Joules/sec=Watts(W)
  21. Humankind's total use of power in 2005
    1.1x10^4 GW
  22. Firt Law of Thermodynamics
    -The change in total internal energy is the sum of heat energy entering the system from its environment plus the work done the system by its environment

    • Δ U = Δ Q + Δ W
    • Δ U= Internal Energy
    • Δ Q= Heat added
    • Δ W= Work done
  23. Entropy
    Measure of a system's unvailability to do work on its environment
  24. Entropy: The more orderd the system
    the lowery its entropy
  25. Entropy: The more disordered the system
    The higher its entropy
  26. The entropy of the universe as a whole
    continously increasing
  27. The entropy of a closed system
    Never decreases
  28. How can the entropy of open systems decrease?
    • Only through the application of work
    • Ex.Cleaning your room
  29. Why heat always flows from hot to cold?
    Increasing entropy
  30. why it's impossible to convert thermal energy to mechanc energy with 100% effiency?
    increasing entropy
  31. Second Law of Thermodynamics
    • 1. In a system, a process that occurs will tend to increase the total entropy of the universe
    • 2. Heat generally cannt flow spontaneously from a mateiral at lower temperature. to a material at higher temperature
    • 3. It is impossible to convert heat completely into work in a cyclic process
Card Set:
E&S: Lecture 1
2012-05-15 23:56:05

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