What does Mercury most resemble in size and appearance?
A. Venus
B. Mars
C. Earth
D. the Moon
Answer: D
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Fourier analysis is something accomplished
A) with all musical instruments. B) automatically by humans. C) both of these D) neither of these
In a shell of a shell and tube heat exchanger with two shell passes and eight tube passes, 12.6 kg/s of water is heated in the shell from 800C to 150°C. Hot exhaust gases having roughly the same physical properties as air enter the tubes at 340°C and leave at 180°C. The total surface, based on the outer tube surface, is 930 m2 . Determine (a) the log-mean temperature difference if the heat exchanger were simple counterflow type, (b) the correction factor F for the actual arrangement, (c) the effectiveness of the heat exchanger, (d) the average overall heat transfer coefficient.
GIVEN
• A tubular heat exchanger with 2 shell passes and 8 tube passes
• Water in the shell, exhaust gases in the tubes
• Exhaust gases have roughly the same physical properties as air
• Water flow rate m w= 12.6 kg/s
• Water temperatures
? Tw,in = 80°C
? Tw,out = 150°C
• Exhaust temperatures
? Te,in = 340°C
? Te,out = 180°C
• Surface are (A) = 930 m2
FIND
(a) LMTD if the exchanger is a simple counterflow type
(b) Correction F for the actual arrangement
(c) Effectiveness (e)
(d) The overall heat transfer coefficient (U)
SKETCH
PROPERTIES AND CONSTANTS
the specific heat of water at the mean temperature of 130°C (cpw) = 4244.5 W/(kg K)
Which of the following best explains why nuclear fusion requires bringing nuclei extremely close together?
A) Nuclei normally repel because they are all positively charged and can be made to stick only when brought close enough for the strong force to take hold. B) Nuclei are attracted to each other by the electromagnetic force, but this force is only strong enough to make nuclei stick when they are close together. C) Nuclei have to be hot to fuse, and the only way to get them hot is to bring them close together. D) Fusion can proceed only by the proton—proton chain, and therefore requires that protons come close enough together to be linked up into a chain.
Your temperature is 98.6°F. Assuming your skin is a perfect radiator (e = 1), determine the wavelength corresponding to the largest intensity (in mm)
a. 8.0 b. 9.3 c. 3.0 d. 5.7 e. 29.4