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Scholar
Karma Points: 200
Respect (73%):
Date Posted: 6/19/2008 8:51:41 PM  Status: Live
Need help one last time!!
Course Textbook Chapter Problem
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Question Details:
Okay,
 
So this question puzzles me when it asks the change in the area:
 
A copper plate has a length of 0.12m and a width of .10m at 25 degrees C.  The plate is uniformly heated to 175 degrees C.  If the linear expansion coefficient for copper is 1.7 x 10  -5/C, what is the change in the area of the plate as a result of the increase in temperature?
 
My answer was .00031m, but I'm not sure.
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Oracle
Karma Points: 15,012
Date Posted: 6/19/2008 9:02:25 PM  Status: Live
Asker's Rating: Lifesaver   
Response:
a = 0.12 m, b = 0.10 m
α = 1.7 x 10-5/C
temperature increased Δt = 175 - 25 = 150 C
αΔt = 2.55 x 10-3
a becomes a' = a*(1 + αΔt) = 0.12*(1 + 2.55 x 10-3) = 0.120306 m
b becomes b' = b*(1 + αΔt) = 0.10*(1 + 2.55 x 10-3) = 0.100255 m
area becomes a'b' = 0.012061278
change = a'b' - ab = 0.000061278 m2
Physics f/Dummies's Comment:
Thanks so much

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Oracle
Karma Points: 13,361
(Santa Fe Community College-New Mexico)
Date Posted: 6/19/2008 9:03:09 PM  Status: Live
Asker's Rating: Helpful   
Response:
ΔA=2αAΔT=2(1.7 x 10  -5/C)( 0.12m)(.10m)(175-25)= 6.12x10-5 m2
Physics f/Dummies's Comment:
Thanks a lot
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