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Unformatted text preview: mperature of the rock and water?
(b) What is the entropy change of the rock?
(c) What is the entropy change of the water?
(d) By how much did the height of the water change due to heating alone (ignoring the bigger effect of the
addition of the rock) if the container has a depth of 2m and a surface area of 0.5m 2? The coefficient of
volume expansion of water is 2x106/°C.
Solutions:
(a) Assume that the final temperature is Tf. c R m ( T f − T ) + c w m w ( T f − T w )= 0
T f= c R mT + c w m w T w
= 303 K
c R m + c w mw
Tf (b) Δ S rock =∫
T Tf (c) Δ S water =∫
Tw c R md T '
T ' = c R mln 303
( TT )=10 ln ( 1500 ) kJ / K =−16 kT / K
f () () c w mw dT
T
303
=c w mw ln f = 4 × 10 3 ln
kJ / K =40 kT / K
T
Tw
300 (d) The change of the volume of the water according to the thermal expansion is ΔV = β V ( T f − T w )= 6 × 10−6 m3
Therefore, the...
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 Spring '08
 Packard
 Physics, Heat

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