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Jennifer001
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1. Homework Statement [/b
the ends of a 20cm long,2cm diameter rod are maintained at 0degrees and 100degrees by immersion in an ice-water bath and boiling water. heat is conducted through the rod at 4.5x10^4J/h. of what material is the rod made?
Q/dt=k(A/L)dT
i first changed the heat energy conducted into watts which is = J/s
4.5x10^4J/h*1h/60min*1min/60s=12.5J/s
then i found the surface area of the rod
A=2(pi0.01^2)+(2pi0.01)0.2=0.01319m^2
now plug it into Q/dt=k(A/L)dT
12.5=k(0.01319)/0.2(100-0)
k=1.895
with this number i found that the rod is made of ice which has a k value of 1.7 (the closest number) but i checked the back and it suppose to be iron which has a k value of 80.. what did i do wrong?
the ends of a 20cm long,2cm diameter rod are maintained at 0degrees and 100degrees by immersion in an ice-water bath and boiling water. heat is conducted through the rod at 4.5x10^4J/h. of what material is the rod made?
Homework Equations
Q/dt=k(A/L)dT
The Attempt at a Solution
i first changed the heat energy conducted into watts which is = J/s
4.5x10^4J/h*1h/60min*1min/60s=12.5J/s
then i found the surface area of the rod
A=2(pi0.01^2)+(2pi0.01)0.2=0.01319m^2
now plug it into Q/dt=k(A/L)dT
12.5=k(0.01319)/0.2(100-0)
k=1.895
with this number i found that the rod is made of ice which has a k value of 1.7 (the closest number) but i checked the back and it suppose to be iron which has a k value of 80.. what did i do wrong?