What will happen in the Sun immediately after it has exhausted its supply of hydrogen in its core?
A) The helium core will shrink, heat, and start helium fusion reactions to produce carbon.
B) With the core hydrogen used up, the Sun will no longer be able to generate energy in any way.
C) The helium core will shrink and heat while hydrogen fusion begins in a shell around the core.
D) The core will collapse, resulting in a supernova.
C) The helium core will shrink and heat while hydrogen fusion begins in a shell around the core.
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Atmospheric pressure air is heated in a long annulus (25-cm-ID, 38-cm-OD) by steam condensing at 149°C on the inner surface. If the velocity of the air is 6 m/s and its bulk temperature is 38°C, calculate the heat transfer coefficient.
GIVEN
Atmospheric flow through an annulus with steam condensing in inner tube
Inside diameter (Di) = 25 cm = 0.25 m
Outside diameter (Do) = 38 cm = 0.38 m
Steam temperature (Ts) = 149°C
Air velocity (V) = 6 m/s
Air bulk temperature (Tb) = 38°C
FIND
The heat transfer coefficient (hc)
ASSUMPTIONS
Steady state
Steam temperature is constant and uniform
Heat transfer to the outer surface is negligible
Air temperature given is the average air temperature
Thermal resistance of inner tube wall and condensing steam is negligible (Inner tube wall surface
temperature = Ts)
SKETCH
PROPERTIES AND CONSTANTS
for dry air at 38°C
Define chunked text and explain the importance of writing scannable text for webpages.
What will be an ideal response?
According to the present estimates, the Universe is about ________ years old.
A. 14 × 105 B. 14 × 107 C. 14 × 1011 D. 14 × 109
You can determine the mass of the Moon
1.by measuring how long it takes to revolve around the Earth. 2.by measuring its distance from the Earth. 3.by measuring its diameter as well as the rate at which objects accelerate due to gravity on the Moon. 4.by doing any of these.