Force on a Moving Charge: A proton is to orbit Earth at the equator using Earth's magnetic field to supply part of the necessary centripetal force. In what direction should the proton move?
A. upward
B. northward
C. southward
D. eastward
E. westward
Answer: E
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According to our present theory of solar system formation, which of the following statements about the growth of terrestrial and jovian planets is not true?
A) Both types of planet begun with planetesimals growing through the process of accretion, but only the jovian planets were able to capture hydrogen and helium gas from the solar nebula. B) Swirling disks of gas, like the solar nebula in miniature, formed around the growing jovian planets but not around the growing terrestrial planets. C) The jovian planets began from planetesimals made only of ice, while the terrestrial planets began from planetesimals made only of rock and metal. D) The terrestrial planets formed inside the frost line of the solar nebula and the jovian planets formed beyond it.
As a treatment for cataracts (a cloudiness of the lens of the eye), the natural lens is removed and a plastic lens is implanted. After this is done a person can see distant objects clearly, but he cannot accommodate to focus on nearby objects
If such a person wanted to read a book at a distance of 25 cm, he would have to wear contact lenses having a diopter power of A) +2.78 diopters. B) +3.33 diopters. C) -1.78 diopters. D) +4.00 diopters. E) -4.00 diopters.
At a particular instant, a proton moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is
A) downward. B) upward. C) zero. D) toward the north. E) toward the south.
In radioactive decay, when the parent material decays to one-quarter of its original amount, the time is
A) one half-life. B) two half-lives. C) three half-lives. D) four half-lives.