How much power does a sphere with a radius of 10 cm radiate into empty space if is has an emissivity of 1.0 and is kept at a temperature of 400 K? (? = 5.67 × 10-8 W/m2 ? K4)
A) 60 W
B) 70 W
C) 180 W
D) 210 W
E) 360 W
C
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After landing on an unexplored Klingon planet, Spock tests for the direction of the magnetic field by firing a beam of electrons in various directions and by recording the following observations:
Electrons moving upward feel a magnetic force in the northwest direction. Electrons moving horizontally toward the north are pushed downward. Electrons moving horizontally toward the southeast are pushed upward. Mr. Spock therefore concludes that the magnetic field at this landing site is in which direction? A) toward the west B) toward the southwest C) toward the east D) toward the northeast E) toward the southeast
As you stand by the side of the road, a car approaches you at a constant speed, sounding its horn, and you hear a frequency of 80.0 Hz. After the car goes by, you hear a frequency of 60.0 Hz
What is the speed of the car? The speed of sound in the air is 343 m/s. A) 25.0 m/s B) 64.0 m/s C) 36.0 m/s D) 16.0 m/s E) 49.0 m/s
Which diagram(s) represent(s) a latitude at which the Sun sometimes remains below the horizon during a full 24-hour period?
What will be an ideal response?
The main drawback of coal as an energy resource is
A) its contribution to the global warming. B) its contribution to the ozone problem. C) limited resources are available. D) its contribution to acid rain. E) the economics associated with the coal industry.