Question

1. Two pots are identical except that the flat bottom of one is aluminum, whereas that of the other is copper. Water in these pots is boiling away at 100.0 ˚C at the same rate. The temperature of the heating element on which the aluminum bottom is sitting is 166 ˚C. Assume that heat enters the water only through the bottoms of the pots and find the temperature of the heating element on which the copper bottom rests.

2. A person's body is producing energy internally due to metabolic processes. If the body loses more energy than metabolic processes are generating, its temperature will drop. If the drop is severe, it can be life-threatening. Suppose a person is unclothed and energy is being lost via radiation from a body surface area of 1.24 m2, which has a temperature of 34 °C and an emissivity of 0.664. Suppose that metabolic processes are producing energy at a rate of 103 J/s. What is the temperature in kelvins of the coldest room in which this person could stand and not experience a drop in body temperature?

3. A solid sphere has a temperature of 611 K. The sphere is melted down and recast into a cube that has the same emissivity and emits the same radiant power as the sphere. What is the cube's temperature in kelvins?

Answer 1

(2) Using Stefon's law Power = € Ao (T" - 12" Area staben's Imissivity constant Volume of Cube 3 103 = 0.664 41.2445.67x108[273+34) 63x109672 2.206x109 = 8.88X108 6.676410? - T2 = (285.8s/kelvin (Temperature of coldest room) (3) volume of sphere 4 TR² (side)3 2.1) sele Now Psphore = Pembe * As of th & Ac of a " ~ 4TR (611)4 = 6 Esile)' I " will +60) = 6&ndeja (7,14 1.123 410" = (T.)" 578.92 Kelvin - R=13 - Tu