Question

.A bar of copper of length 0.75m and a bar of steel of length 1.25m are joined together end to

end. Both are of circular cross section with diameter 2 cm. Free ends of the copper and steel

are maintained at 1000 C and 0

0C respectively. The surfaces of the bars are thermally insulated.

What is the temperature of the copper-steel junction? What is the heat transmitted per unit time

across the junction? Thermal conductivity of copper = 358 Wm-1 K-1

and that of steel

= 46 Wm-1 K-1

.
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Answer 1

Answer:

Answer :

[93∘C;1.07j/s]

Solution :

Let θ∘C be the temperature of the junction, Fig. 7(e).22. As (ΔQ/Δt) for both the rods is the same, therefore

ΔQΔt=KcuA(100∘−θ)0.75=(KsteelAθ−0∘1.25  

∴386(100∘−θ)3=46θ5 or θ=93∘C

Rate of heat flow =ΔQΔt=KsteelAθ1.25

=46×π(0.1)2×931.25=1.07j/s

Explanation: