Determine the Fourier coefficient, An , for the problem resulting in a temperature
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The public debate about Martian canals was not resolved until
A) many scientists were unable to reproduce Percival Lowell's sketches of Martian canals B) the governing body of astronomy, the International Astronomical Union made an official statement on the matter C) the first spacecraft flew past Mars in 1965 D) the first spacecraft landed on Mars in 1976
If the magnification of a mirror is negative, which of the following is correct?
A) The image is upright and the mirror is convex. B) The image is inverted and the mirror is convex. C) The image is inverted and the mirror is concave. D) All of the previous answers can be correct. E) None of the previous answers is correct.
A 1-m-square copper plate is placed horizontally on 2-m-high legs. The plate has been coated with a material that provides a solar absorptivity of 0.9 and an infrared emissivity of 0.25. If the air temperature is 30°C, determine the equilibrium temperature on an average clear day in which the solar radiation incident on a horizontal surface is 850 W/m2
GIVEN
• A horizontal copper plate in air
• Plate dimensions (s × s) = 1 m × 1 m
• Solar absorptance (?s) = 0.9
• Infrared emittance (?) = 0.25
• Air temperature (T?) = 30°C = 303 K
• Incident solar radiation (qs/A) = 850 W/m2
FIND
• Equilibrium Temperature (Ts)
ASSUMPTIONS
• The sky behaves as a black body at 0 K
• The effect of the legs is negligible
• Air is quiescent
• Radiative heat transfer from the bottom of the plate is negligible
SKETCH
PROPERTIES AND CONSTANTS
The Stephan-Boltzmann constant (?) = 5.67 ? 10–8 W/(m2 K4
The Sun's rays strike the surface of the Earth at 90 degrees at the ____________ on December 22.
What will be an ideal response?