Why does SETI concentrate on the water hole?
What will be an ideal response?
The interval between the H and hydroxyl molecules is a very quiet part of the radio spectrum.
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The high _______________ of quasars reveals to astronomers that they must be very distant
Fill in the blank(s) with correct word
It is possible that there are moons within habitable zones that have habitable surfaces in other solar systems
Indicate whether the statement is true or false
Why can we never create matter?
A) because matter is always conserved B) because energy is always conserved C) because it is impossible to create the fundamental particles such as electrons and protons D) because we aren't capable of creating another universal "big bang" E) Actually, we do create matter frequently in the lab.
A black sphere (2.5-cm in diameter) is placed in a large infrared heating oven whose walls are maintained at 370°C. The temperature of the air in the oven is 90°C and the heat-transfer coefficient for convection between the surface of the sphere and the air is 30 W/(m2 K). Estimate the net rate of heat flow to the sphere when its surface temperature is 35°C.
GIVEN
• A black sphere in a large infrared heating oven
• Sphere diameter (D) = 2.5 cm = 0.025 m
• Oven wall temperature (T2) = 370°C = 643 K
• Oven air temperature (T?) = 90°C = 363 K
• Convective heat transfer coefficient (hc) = 30 W/(m2 K)
• Sphere surface temperature (T1) = 35°C = 308 K
FIND
• The net rate of heat flow to the sphere (qtotal)
ASSUMPTIONS
• The oven walls are diffuse
SKETCH
PROPERTIES AND CONSTANTS
the Stephan-Boltzmann constant (?) = 5.67 × 10–8 W/m2K4