To say that one wave is out of phase with another is to say that the waves are
A) of different amplitudes.
B) of different frequencies.
C) of different wavelengths.
D) out of step.
E) all of the above
Answer: D
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To say that water has a high specific heat capacity is to say that water
A) requires a lot of energy for an increase in temperature. B) releases a lot of energy in cooling. C) absorbs a lot of energy for an increase in temperature. D) all of the above
Why are telescopes sometimes called "time machines"?
A) because the author, H.G. Wells, used the term to describe telescopes in a book B) because some of the oldest telescopes are still in use today C) because observations of distant objects reveal them as they were in the past D) because astronomers can use telescopes to see the Milky Way as it was when it was much younger E) It's a journalistic misnomer: you cannot travel into the past or the future.
At what angle is the orbit of the Moon around Earth inclined with respect to the orbital plane of Earth around the Sun?
Atmospheric air at a velocity of 61 m/s and a temperature of 16°C enters a 0.61-m-long square metal duct of 20 × 20 cm cross section. If the duct wall is at 149°C, determine the average heat transfer coefficient. Comment briefly on the L/Dh effect.
GIVEN
Atmospheric air flow through a square metal duct
Air velocity (V) = 61 m/s
Inlet air temperature (Tb,in) = 16°C
Duct dimensions: 20 cm × 10 cm × 0.61 m = 0.2 m × 0.2 m × 0.61 m
Duct wall surface temperature (Ts) = 149°C
FIND
The average heat transfer coefficient (c h)
ASSUMPTIONS
Steady state
Constant and uniform wall surface temperature
SKETCH
