1) Suppose 150 W of heat flows by conduction from the blood capillaries beneath

Question

1) Suppose 150 W of heat flows by conduction from the blood capillaries beneath the skin to the body's surface area of 1.7 m2.

Part A

If the temperature difference is 0.50C, estimate the average distance of capillaries below the skin surface.

Express your answer to two significant figures and include the appropriate units.

2) A 0.40-kg iron horseshoe, just forged and very hot(Figure 1) , is dropped into 1.25 L of water in a 0.35-kgiron pot initially at 20.0C. The value of specific heat for iron is 450 J/kgC , and for water is 4186 J/kgC

Part A

If the final equilibrium temperature is 25.0 C, Determine the initial temperature of the hot horseshoe.

Express your answer using two significant figures.

Please show all work

Explanation / Answer

1)Given

Power = P = 150 W ; Area = A = 1.7 m2

T = 0.5 deg C ;

let L be the average distance.

We know that, rate of change of heat flow:

dQ/dt = P = k A T / L

where, k is the thermal conductivity ; A is the surface area ; T is temperaure difference and L is the distance.

L = k A T / P

L = 0.2 J/m deg C x 1.7 m2 x 0.5 deg C / 150 = 0.00113 m = 1.13 mm

Hence, the distance of the capillary is = L = 0.00113 m = 1.13 mm.

[A humble request to put the other question seperately. Let me know for any query... Thanks]

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