MasteringPhysics19a

MasteringPhysics19a - MasteringPhysics: Assignment Print...

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MasteringPhysics: Assignment Print View http://session.masteringphysics.com/myct/assignmentPrint?assignmentI. .. 1 of 9 12/19/2007 1:06 PM [ Print View ] PHCC 141: Physics for Scientists and Engineers I - Fall 2007 19a. First Law of Thermodynamics Due at 11:59pm on Thursday, November 29, 2007 Hide Grading Details Number of answer attempts per question is: 5 You gain credit for: correctly answering a question in a Part, or correctly answering a question in a Hint. You lose credit for: exhausting all attempts or requesting the answer to a question in a Part or Hint, or incorrectly answering a question in a Part. Late submissions: reduce your score by 100% over each day late. Hints are helpful clues or simpler questions that guide you to the answer. Hints are not available for all questions. There is no penalty for leaving questions in Hints unanswered. Grading of Incorrect Answers For Multiple-Choice or True/False questions, you lose 100% / ( # of options - 1 ) credit per incorrect answer. For any other question, you lose 3% credit per incorrect answer. First Law of Thermodynamics The First Law of Thermodynamics Derived Learning Goal: To understand the first law of thermodynamics and its origin. The first law of thermodynamics generalizes the concept of energy conservation to include heat energy. You probably already appreciate that loss of total mechanical energy (e.g., from nonconservative forces such as friction) does not destroy energy, but rather converts mechanical energy to heat. This process can be described quantitatively by the first law. By relating heat, internal energy, and work, the first law lays the groundwork for thermodynamics, a field that also explains the conversion of heat into mechanical energy. Like the law of mechanical energy conservation that it generalizes, the first law relates the changes in energy that occur from the beginning to the end of some process. The first law involves changes in the following physical quantities: : work done by the system on the outside world, : heat added to the system by the outside world, and : internal energy change of the system. You need to look carefully at the wording used here; some other disciplines (chemistry comes to mind) may use other definitions. Part A Which of the following is the sign convention that results from these definitions? ANSWER: is positive when the system is compressed, and is positive when heat is added to the system. is positive when the system expands, and is positive when heat is added to the system. is positive when the system is compressed, and is positive when heat is taken from the system. is positive when the system expands, and is positive when heat is taken from the system. Part B
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This note was uploaded on 10/28/2008 for the course PH 141 taught by Professor Toki during the Fall '08 term at Colorado State.

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MasteringPhysics19a - MasteringPhysics: Assignment Print...

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