The density wave theory explains spurs and branches along the spiral arms
a. True
b. False
Indicate whether the statement is true or false
False
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A long nonconducting cylinder (radius = 6.0 mm) has a nonuniform volume charge density given by ?r2, where ? = 6.2 mC/m5 and r is the distance from the axis of the cylinder. What is the magnitude of the electric field at a point 2.0 mm from the axis?
A. 1.4 N/C B. 1.6 N/C C. 1.8 N/C D. 2.0 N/C E. 5.4 N/C
You carry a 20-N box 5 m horizontally across a room. The work you do is
a. 0 b. 4 J. c. 100 J. d. none of the above.
An inventor has created a heat engine that extracts energy from geothermal hotspots and geysers like Old Faithful at Yellowstone National Park. She claims to turn all of the geothermal energy into work. Such a device is
A. a violation of the first law of thermodynamics. B. consistent with Clausius's statement of the second law of thermodynamics. C. a violation of Kelvin's statement of the second law of thermodynamics. D. only possible for a Carnot cycle.
A bar magnet is dropped from above and falls through the loop of wire shown below. The north pole of the bar magnet points downward towards the page as it falls. Which statement is correct?
A. The current in the loop always flows in a clockwise direction. B. The current in the loop always flows in a counterclockwise direction. C. The current in the loop flows first in a clockwise, then in a counterclockwise direction. D. The current in the loop flows first in a counterclockwise, then in a clockwise direction. E. No current flows in the loop because both ends of the magnet move through the loop.