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Unformatted text preview: ME 201 Exam No. 1 February 11, 2008 Name: 50 i M L a” I’II‘S'tudent Number: Instructions There are three problems. Allocate your time and effort to maximize your points.
Layout your work clearly and show your reasoning. This is an openbook (Text Book) examination. One 8% x 1 1 paper with your notes allowed. Problem 1 (20 points) (a) What is the difference between intensive and extensive properties? (5 points) In+em5.‘t/o_ 'PmPvt’xVh‘ﬁs 0W2. im <Lefenaen1— 01’: ‘HUL mass of asygte Exiewscua properties are ﬁreﬂy/ﬂew +0 m was <95; asygira (b) How many independent intensive properties are required to completely specify the state of a
simple compressible system? (5 points) 2 . (c) A rock is dropped from an elevation of 10 m (10 m above the ground). What is the velocity of
the rock when it is 5 m from the ground? (5 points) 2.
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= m («n/g) (d) Can quality be expressed as the ratio of the volume occupied by the vapor phase t
volume? Explain. (5 points) N0.
Tm We is (Lefwd, as “HI,2 mm of m massgaﬁ, We VQFW PM +0 44.42 W mass 0 the total 9 Problem 2 (40 points) The volume of 1 kg of air in a pistoncylinder device is initially 1.722 m3. Now the air is
compressed to 0.861 III3 while its pressure is maintained constant at 200 kPa. Determine (a) the initial and ﬁnal temperatures of the air, (10 points)
(b) the work required to compress the air, ( 10 points)
(c) the net heat transfer during the process, is the system losing heat or gaining heat? (15 points)
(d) Draw the process on a P — v diagram. (5 points)
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Problem 3 (40 points) Ca
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A rigid container with a volume of 0.2 m3 is initially ﬁlled with steam at 200 kPa and 400" C. It
is then cooled to 90° C.
(a) What are the internal energy and speciﬁc volume of the initial state? (10 points) (b) Give the phase description of the ﬁnal state and calculate the quality, x, (if applicable) of
the water in the ﬁnal state? (10 points)
(c) What is the mass of the water in the tank? (5 points)
(d) What is the amount of the heat transfer during the cooling process? (10 points)
(e) Draw the process on a T — v diagram with respect to the saturation lines. ( 5 points)
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