Which event in the history of the universe happened last?
A) Stable helium nuclei formed.
B) The electroweak force separated into electromagnetic and weak nuclear forces.
C) The GUT force separated into the electroweak force and strong force.
D) Neutral atoms formed.
D
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Which of the following explains why navigators prior to a few hundred years ago found it much more difficult to determine longitude than latitude?
A) Determining longitude requires mathematical techniques that were not known at the time. B) Determining longitude requires much more precise measurements of angles in the sky than does latitude. C) Determining longitude requires accurate tables of the celestial coordinates of stars, while determining latitude does not. D) Determining longitude requires an accurate clock, but latitude does not.
An ideal transformer has 50 turns in the primary and 500 turns in the secondary. An input of 12 V will produce an output of
A) 12 V. B) 120 V. C) 1200 V. D) none of the above
You may have noticed that when you get out of a swimming pool and stand dripping wet in a light breeze, you feel much colder than you feel after you dry off. Why is this?
A) The moisture on your skin has good thermal conductivity. B) Water has a relatively large heat capacity. C) This is a purely psychological effect resulting from the way in which sensory nerves in the skin are stimulated. D) The water on your skin is colder than the surrounding air. E) 540 calories of heat are required to evaporate each gram of water from your skin, and most of this heat flows out of your body.
Two chemical structures are shown, one of a typical gasoline molecule and the other of a typical motor oil molecule. Which is which?
Base your reasoning not on memorization but rather upon what you know about molecular interactions and the various physical properties of gasoline and motor oil. A) Structure A represents the gas molecule because there are more bonds to gain energy from, giving it a higher energy content than oil. B) Structure A represents motor oil, illustrating a molecule with greater induced dipole-induced dipole molecular interactions thus, the molecules are strongly attracted to one another. C) Structure B represents the oil molecule. Because oil molecules are smaller, they can compact closer together, giving the appearance of a thicker solution than gasoline. D) Structure B represents crude oil which is processed to generate longer molecules of gasoline to prevent toxic vapors from harming consumers.