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Chapter 17

Chapter 17. Accounting Concepts. counting. Systems. A system is a subset of the universe defined by an engineer for the solution of a problem. See Figure 17.3. System Rules. The system cannot be changed midway through the calculation. The system can be any shape.

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Chapter 17

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  1. Chapter 17 Accounting Concepts counting

  2. Systems • A system is a subset of the universe defined by an engineer for the solution of a problem. • See Figure 17.3.

  3. System Rules • The system cannot be changed midway through the calculation. • The system can be any shape. • The system can be rigid or flexible.

  4. What is the difference between “counting” and “measuring”?

  5. Extensive Quantities • Quantities in an engineering problem that accumulate or deplete • Quantities that are counted • Example: mass

  6. Intensive Quantities • Quantities in an engineering problem that represent a level or state of a process or object • Quantities that are measured • Example: pressure

  7. Team Exercise Label each of these quantities as extensive (countable) or intensive (describes the state): • moles • elevation • volume • energy • temperature • power • area • density • charge • color • pressure • money

  8. What do engineers count? • Mass • Charge • Energy • Momentum (Linear and Angular) • Entropy • Money

  9. System Rules • The ratio of two extensive quantities is intensive. What’s an example of this? Rules 5 through 9 “Let’s focus on the first 4.”

  10. Homogenous and Heterogeneous (Uniform) (Lumpy)

  11. Open and Closed Systems • Closed systems: mass does not cross the boundaries of a closed system • Open systems: mass is allowed to cross boundaries in an open system

  12. Team Exercise Label each of these systems as a closed or open system. • rifle • rifle and bullet • rocket • automobile engine • truss • mailbox • remote control • rock • stapler • Sun • telescope Most systems are open systems but can be considered to be closed during a short time when solving engineering problems.

  13. Universal Accounting Equation The UAE is: Final State - Initial State = Input - Output + Generation - Consumption

  14. Definitions (section 17.7) • Final State: specifies the amount of an extensive quantity at the end of the time period. • Initial State: specifies the amount of an extensive quantity at the beginning of the time period.

  15. Definitions • Input: specifies the amount of an extensive quantity added to the system during the time period. • Output: specifics the amount of an extensive quantity leaving the system during the time period. • Generation: specifies an amount of an extensive quantity produced in a system during a time period. • Consumption: specifies an amount of an extensive quantity destroyed in a system during a specific time period.

  16. Team Exercise (10 min.) • On Dec. 1, 1998 the balance in a money market account was $498.65. Monthly activity: $1257.86 deposits, $5.42 interest, $945.78 checks, $300.00 cash from ATM, $8.00 in service charges. • What is the system and the extensive quantity? • What is the output, input, generation, consumption, and final balance as of Jan. 1?

  17. Team Exercise • Chicken production -- A chicken coop is examined for a one year period. The coop starts with 34,000 chickens. • During the year: • 16,000 are purchased, • 20,000 are sold, • 12,000 are hatched, • 263 disappear, lost or died • What is the final state?

  18. The Chicken Coop 16,000 chickens 20,000 chickens Definitions for the coop: Initial state =34,000 Net input =16,000 - 20,000 =-4,000 Net generation = 12,000 - 263 =11,737 Final state =41,737 Accum. =41,737 - 34,000 = 7,737 34,000 chickens 12,000 chickens 263 chickens Boundary Coop

  19. RAT (Individual) • The 1980 and 1990 census of the Hometown, USA found that the population was 8,926 and 10,112, respectively. During that 10 year period the Chamber of Commerce reported that 945 people had moved in, 108 people had moved out and that there were 516 births. • As an INDIVIDUAL take 10 minutes to determine: a) accumulation b)net input, and c)net generation from 1980 to 1990.

  20. Universal Accounting Equation The UAE is: Final State - Initial State = Input - Output + Generation - Consumption

  21. Related Equations • Accumulation = Final State - Initial State • Net Input = Input - Output • Net Generation = Generation - Consumption • Then an alternate form of the UAE becomes: Accumulation = Net Input + Net Generation

  22. UAE for Common Systems • Steady state systems: Final state = Initial State and Accumulation = 0

  23. Team Exercise • Chicken production -- A farmer wishes to operate his chicken coop at steady state. During the year: • 16,000 are purchased, • 12,000 are hatched, • 20 are eaten by foxes • How many should be sold?

  24. UAE for Common Systems • Conservative Systems: Generation = 0 Consumption = 0 Final State - Initial State = Input - Output

  25. Next Chapter…

  26. Team Exercise • Chicken production -- A farmer wishes to operate his chick coop at steady state. During the year: • 16,000 are purchased, • 12,000 are hatched, • 20 are eaten by foxes • How many should be sold?

  27. Project Two Stirling Engine

  28. HomeworkNote: Bring your book, homework, and calculator to class on Thursday.

  29. Chapter 17 Accounting Concepts counting

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