Chapter 12: Problem 7
Why do skiers get sunburned so easily?
Short Answer
Step by step solution
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Chapter 12: Problem 7
Why do skiers get sunburned so easily?
These are the key concepts you need to understand to accurately answer the question.
All the tools & learning materials you need for study success - in one app.
Get started for freeSolar radiation is incident on the front surface of a thin plate with direct and diffuse components of 300 and \(250 \mathrm{~W} / \mathrm{m}^{2}\), respectively. The direct radiation makes a \(30^{\circ}\) angle with the normal of the surface. The plate surfaces have a solar absorptivity of \(0.63\) and an emissivity of \(0.93\). The air temperature is \(5^{\circ} \mathrm{C}\) and the convection heat transfer coefficient is \(20 \mathrm{~W} / \mathrm{m}^{2} \cdot \mathrm{K}\). The effective sky temperature for the front surface is \(-33^{\circ} \mathrm{C}\) while the surrounding surfaces are at \(5^{\circ} \mathrm{C}\) for the back surface. Determine the equilibrium temperature of the plate.
Solar radiation is incident on the outer surface of a spaceship at a rate of \(400 \mathrm{Btu} / \mathrm{h} \cdot \mathrm{ft}^{2}\). The surface has an absorptivity of \(\alpha_{s}=0.10\) for solar radiation and an emissivity of \(\varepsilon=0.6\) at room temperature. The outer surface radiates heat into space at \(0 \mathrm{R}\). If there is no net heat transfer into the spaceship, determine the equilibrium temperature of the surface
A radiometer can be used to determine the position of an approaching hot object by measuring the amount of irradiation it detects. Consider a radiometer placed at a distance \(H=0.5 \mathrm{~m}\) from the \(x\)-axis is used to measure the position of an approaching small blackbody object. If the radiometer is measuring \(80 \%\) of the irradiation corresponding to the position of the object directly under the radiometer \((x=0)\), determine the position of the object \(L\).
The absorber surface of a solar collector is made of aluminum coated with black chrome ( \(\alpha_{s}=0.87\) and \(\left.\varepsilon=0.09\right)\). Solar radiation is incident on the surface at a rate of \(600 \mathrm{~W} / \mathrm{m}^{2}\). The air and the effective sky temperatures are \(25^{\circ} \mathrm{C}\) and \(15^{\circ} \mathrm{C}\), respectively, and the convection heat transfer coefficient is \(10 \mathrm{~W} / \mathrm{m}^{2} \cdot \mathrm{K}\). For an absorber surface temperature of \(70^{\circ} \mathrm{C}\), determine the net rate of solar energy delivered by the absorber plate to the water circulating behind it.
A furnace that has a \(40-\mathrm{cm} \times 40-\mathrm{cm}\) glass window can be considered to be a blackbody at \(1200 \mathrm{~K}\). If the transmissivity of the glass is \(0.7\) for radiation at wavelengths less than \(3 \mu \mathrm{m}\) and zero for radiation at wavelengths greater than \(3 \mu \mathrm{m}\), determine the fraction and the rate of radiation coming from the furnace and transmitted through the window.
What do you think about this solution?
We value your feedback to improve our textbook solutions.