Different units can be used for length: m and cm, and of these two, m is the larger by a factor of 100 . Different units can also be used for R: (1) J/mol/K, (2) L/atm/mol/K, and (3) (N/m2)/m3/mol/K. Which of these units for R is the largest? Hint: When expressing R in each of these units, which expression has the lowest numerical factor? (1 L = 10?3 m3, 1 atm = 1.01 × 10^5 Pa)
a. 1
b. 2
c. 3
d. They are all equal.
b
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A steel with a small grain size has a _________yield strength than the same steel with a larger grain size.
Fill in the blank(s) with the appropriate word(s).
The equation has been proposed by Hausen for the transition range (2300 < Re < 8000) as well as for higher Reynolds numbers. Compare the values of Nu predicated by Hausen’s equation for Re = 3000 and Re = 20,000 at D/L = 0.1 and 0.01 with those obtained from Gnielinski correlation. Assume the fluid is water at 15°C flowing through a pipe at 100°C.
GIVEN
• Water flowing through a pipe
• The Hausen correlation given above
• Water temperature = 15°C
• Pipe temperature = 100°C
FIND
• The Nusselt number using the Hausen correlation and appropriate equations and charts in the text for Re = 3000 and 20,000 and D/L = 0.1 and 0.01
ASSUMPTIONS
• Steady state
• Constant and uniform pipe temperature
SKETCH
PROPERTIES AND CONSTANTS
for water at 15°C
Absolute viscosity (?b) = 1136 × 10–6 (Ns)/m2
Prandtl number (Pr) = 8.1 At 100°C ?s = 277.5 × 10–6 (Ns)/m2
Prs= 1.75
The type of smog that forms in Los Angeles is called ______________ smog
a. photochemical b. exhaust c. biochemical d. exhaugenic
Spiral arms appear bright because
A) they contain more hot young stars than other parts of the disk. B) they contain far more stars than other parts of the galactic disk. C) they contain more molecular clouds than other parts of the disk. D) they are the only places where we find stars within the disk of the galaxy.