Problem 1: Experts on hypothermia tell us that heat loss from the body is much greater in 10°C water than in air at the same tem
perature. To test this, assume that heat transfer from a person can be approximated as that from a vertical cylinder of diameter D = 0.3 m and length L = 1.8 m, with a constant surface temperature of 37°C. Assuming that heat losses from the cylinder occur only at the lateral surfaces, calculate the ratio of the heat transfer rate from the cylinder to water to that for the cylinder to air. Data for the heat transfer properties for water and air can be found in the Appendix in Tables A.2-11 and A.3-3, respectively, and appropriate correlations can be found in eqns (4.7-4), and Tables 4.7-1 and 4.7-2. What do you conclude from this about your odds of survival if you fall into a cold water lake/ocean? (Hint: neglect the cylinder height restriction in Table 4.7-1).
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Answer:
Complete question for your reference is below.
A milling operation was used to remove a portion of a solid bar of square cross section. Forces of magnitude P = 19 kN are applied at the centers of the ends of the bar. Knowing that a = 28 mm and sigma_all = 130 MPa, determine the smallest allowable depth d of the milled portion of the bar
Explanation:
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Answer:
The chip will operate below a maximum allowable temperature of 85°C
Explanation:
<em>Given data:</em>
8-mm-thick aluminum
0.02 mm-thick epoxy joint
chip and substrate = 10 mm on a side
temperature = 25°C
attached below is a detailed solution
Tc = 75.3 ° c which is less than 85°c . hence the chip will operate below a maximum allowable temperature of 85°C
