BackA copper rod and an aluminum rod of the same length and cross-sectional area are attached end to end (Fig. 19–35). The copper end is placed in a furnace maintained at a constant temperature of 205°C. The aluminum end is placed in an ice bath held at a constant temperature of 0.0°C. Calculate the temperature at the point where the two rods are joined.
The ends of a 20-cm-long, 2.0-cm-diameter rod are maintained at 0°C and 100°C by immersion in an ice-water bath and boiling water. Heat is conducted through the rod at 4.5×104 J per hour. Of what material is the rod made?
A house has a volume of 1200 m³. What is the total mass of air inside the house at 15°C?
A spherical pot contains L of hot coffee (essentially water) at an initial temperature of °C. The pot has an emissivity of , and the surroundings are at °C. Calculate the coffee's rate of heat loss by radiation.
In a cold environment, a person can lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the body temperature to drop from 36.6°C to 35.6°C if metabolism were nearly to stop. Assume a mass of 65 kg. (See Table 19–1.)
A leaf of area 40cm2 and mass 4.5 x 10-4 kg directly faces the Sun on a clear day. The leaf has an emissivity of 0.85 and a specific heat of 0.80 kcal/kg K. Estimate the rate of rise of the leaf’s temperature.
(a) Using the solar constant, estimate the rate at which the whole Earth receives energy from the Sun. (b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter, (∈ = 1.0) estimate its average surface temperature. [Hint: Discuss why you use area A = πr²E or A = 4πr²E in each part.]