Homework 5
Phys 416
Due
: Friday, Oct. 1, 2010, at 3:00 pm in Room 144.
Note
: On your HW write: “
PHYS 416 HW, Grader Marius Radu
”
Do problems 5.6, 5.8, 5.10, 6.1, 6.2 in the text.
Additional problems:
A. Heat capacity of a penny
(a)
Please find the specific heat capacity of a penny using general equations
obtained in Debye approximation for solids at high temperatures (Lecture 7).
Assume that a penny is solid copper (true for pennies made before 1857), and
use copper atomic weight of 63.55 g/mol. Compare that theoretical prediction of
Gibbs model with the measured heat capacity of copper at various temperatures
(Rev. Sci. Instrum. 58 (1987) 639):
T(K) – C (J/g
.
K)
20 K – 0.007
100 K – 0.252
280 K – 0.381
300 K – 0.385 (~room temperature)
320 K – 0.388
(b)
Since 1982 penny is 97.5 % zinc (core) coated with
2.5% copper (you can ignore copper). Would the heat
capacity (in J/gK) of a zinc penny be much different from
that of a copper penny? (atomic weight of zinc is 65.39
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 Spring '10
 SAVIKHIN
 Physics, Thermodynamics, Work, Heat, Rev. Sci

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