When we see a meteor shower, it means that
A) Earth is crossing the orbit of a comet.
B) the solar wind is unusually strong.
C) an Earth-approaching asteroid has recently come close to our planet.
D) you should duck and run for cover to avoid being blasted on the head by a rock from space.
A) Earth is crossing the orbit of a comet.
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In order for the angular momentum of a rotating object to be conserved
A. Net force must be zero B. Net force must be constant, but not equal to zero C. Net torque must be zero D. Net torque must be constant, but not equal to zero
A negatively charged grain of soot released between the parallel plates of a capacitor moves leftward. The potential between the parallel plates ________ (indicate whether it increases, decreases, or stays the same) from right to left, and the potential energy of the negatively charged grain of soot ________ (indicate whether it increases, decreases, or stays the same) from right to left.
Fill in the blank(s) with the appropriate word(s).
When the Moon is on the horizon, it appears larger than when it is high in the sky. Why?
A. Its angular size is larger on the horizon. B. This is an optical illusion. C. When it is on the horizon, it is closer to us. D. The brightness of the Moon makes it seem larger. E. Earth's atmosphere acts like a lens, magnifying it.
Two solenoids are each made of 2000 turns of copper wire per meter. Solenoid I is 2 m long, while solenoid II is 1 m long. When equal currents are present in the two solenoids, the ratio of the magnetic field BI along the axis of solenoid I to the magnetic field BII along the axis of solenoid II, BI/BII, is
A. 1/4. B. 1/2. C. 1. D. 2 E. 4.