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square steel bar of side length w= 0.12 m has a thermal conductivity of k= 14.6

ID: 1500893 • Letter: S

Question

square steel bar of side length w= 0.12 m has a thermal conductivity of k= 14.6 J(s.m.degrees C) and is L= 2.5 m long. One end is placed under a candle so that the temperature is T1= 99 degrees C while the other end rests on a block of ice so that the temperature is a constant T2.

A)Input an expression for the heat transferred to the cold end of the bar as a function of time, using A= w2 as the cross-sectional area of the bar

. B) How much energy, in joules, was conducted in 1 hour, assuming T2 = 0 degrees C.

C) Input an expression for the mass of water melted in 1 hour using Q1 from above and Lf the latent heat of fusion. Comment

Explanation / Answer

A)

heat transfered is given by

Q/t = kA(T1-T2)/L

A = w^2

k = 14.6

T1= 99

therefore

Q= t xk w^2 (T2-T1)/L

B)

substituting given values

t = 60x60 sec = 3600sec

Q = 29971.8144 J

C)

we know that

Q = mLf

m = Q/Lf

m = 29971.8/ Lf