What causes the radio pulses of a pulsar?
A) The star vibrates.
B) As the star spins, beams of radio radiation sweep through space. If one of the beams crosses Earth, we observe a pulse.
C) The star undergoes periodic explosions of nuclear fusion that generate radio emission.
D) The star's orbiting companion periodically eclipses the radio waves emitted by the main pulsar.
E) A black hole near the star absorbs energy and re-emits it as radio waves.
B
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A thin 2.00-m string of mass 50.0 g is fixed at both ends and under a tension of 70.0 N. If it is set into small-amplitude oscillation, what is the frequency of the first harmonic mode?
A) 6.61 Hz B) 13.2 Hz C) 26.5 Hz D) 52.9 Hz
Conversion of Units: There are 640 acres in a square mile, and 5280 feet in 1.00 mile. What is the length in feet (to the nearest foot) of the side of a square having an area of 1.00 acre?
A. 660 feet B. 209 feet C. 165 feet D. 412 feet E. 435 feet
A uniform meter stick with a mass of 135 g rotates about an axis perpendicular to the stick passing through the center of the stick with an angular speed of 3.50 rad/s2. What is the magnitude of the angular momentum of the stick?
A) 0.0394 kg?m2/s B) 0.473 kg?m2/s C) 0.0739 kg?m2/s D) 0.158 kg?m2/s E) 0.0236 kg?m2/s
Amy, Brad, and Cate are walking (or running) along a straight line as represented below