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HomeworkAssignment+1

# HomeworkAssignment+1 - That is why there is volume...

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Louisiana State University Mechanical Engineering Department Professor Meletis ME 2733 Fall 2004 Assignment #1 (Due: Wednesday, September 8, 2004) 1. Assume the potential energy (V) between atoms in a solid can be represented by the expression: 4 2 a B a A V + = where “ a ” is the interatomic distance and A and B are constants. Calculate the bonding energy V o in terms of the parameters A and B using the following steps: (a) Differentiate V with respect to a, and then set the resulting expression equal to zero. Note that V versus a is minimum at V o . (b) Solve the previous expression for a in terms of A and B . This yields a o , the equilibrium interatomic distance. (c) Obtain the expression for V o by inserting a o in the equation given above. 2. Give the shorthand electron notation for the elements Zn, Co, K, N, and Ge. 3. On the basis of the hydrogen bond, explain the anomalous behavior of water when it freezes.
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Unformatted text preview: That is why there is volume expansion upon solidification. 4. The thermal expansion coefficient and elastic moduli for several metals are listed below. Make a plot of the expansion coefficient as a function of elastic modulus. (a) Describe qualitatively the basis for the correlation that is observed. (b) What is your expectation for the variation in the melting point of these metals? Justify your answer. (c) Provide qualitative F (interatomic force) vs a (interatomic distance) and V (interatomic potential) vs a graphs for Ni and Mo and indicate which features of the graphs relate to their different physical properties (thermal expansion, elastic modulus and melting point). Thermal expansion Elastic modulus Metal Coefficient ( o C-1 x10 6 ) (10 3 ksi) A l 1 1 2 4 C u 1 8 1 8 N i 2 6 1 3 Cr 6.2 36 Li 56.0 1.6 Mo 4.9 47 K 83.0 0.51 Na 71.0 1.3 W 4.6 56.4...
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