Where does the celestial equator intersect the ecliptic?
A. at the zenith
B. at the southern horizon
C. at the summer solstice
D. at the equinoxes
at the equinoxes
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A food calorie is a kilocalorie in SI units. What would be the speed of a 1000 kg car traveling such that its kinetic energy is equal to the energy contained in one 250-calorie jelly doughnut?
A. 46 m/s B. 65 m/s C. 32 m/s D. 22 m/s
Nuclear Binding Energy: A beryllium-8 nucleus at rest undergoes double alpha decay as follows:
The known atomic masses are:
What is the kinetic energy of each departing alpha particle? (1 u = 931.5 MeV/c2)
A. 46 keV B. 65 keV C. 92 keV D. 130 keV E. 180 keV
The refrigeration system for an indoor ice rink is to be sized by an HVAC contractor. The refrigeration system has a COP (coefficient of performance) of 0.5. The ice surface is estimated to be –2°C and the ambient air is 24°C. Determine the size of the refrigeration system in kW required for a 110 m diameter circular ice surface.
GIVEN
? Round ice rink
? Diameter (D) = 110 m
? Ice surface temperature (Ts) = – 2°C
? Air temperature (T?) = 24°C
? COP of refrigeration system = 0.5
FIND
? Size of the refrigeration system required
ASSUMPTIONS
? Air is quiescent
? The effects of sublimation are negligible
? Radiation heat transfer is negligible
SKETCH
PROPERTIES AND CONSTANTS
From Appendix 2, Table 28, for dry air at the mean temperature of 11°C
The radio waves emitted from Sagittarius A* region take how long to travel to Earth?
A. 220 million years B. 50,000 years C. 100,000 years D. 8.5 years