Coulomb's Law: An electron and a proton are released simultaneously from rest and start moving toward each other due to their electrostatic attraction, with no other forces present. Which of the following statements are true just before they are about to collide? (There could be more than one correct choice.)
A. They are closer to the to the initial position of the electron that to the initial position of the proton.
B. They are closer to the to the initial position of the proton that to the initial position of the electron.
C. They are at the midpoint of their initial separation.
D. They both have the same speed.
E. The electrostatic force on the proton is greater than the electrostatic force on the electron.
Answer: B
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The orbits of most comets:
A) are like the planets, fairly circular and in the ecliptic plane. B) lie almost entirely beyond the orbit of Neptune. C) have perihelions within the orbits of Mercury. D) go no farther out than Pluto, then return to the Sun again. E) are shorter than the 76 year period for Comet Halley.
The Bernoulli effect is responsible for the lift force on an airplane wing. Wings must therefore be designed so as to insure that
A) air molecules will be deflected downward when they hit the wing. B) air molecules will be deflected upward when they hit the wing. C) air molecules move more rapidly past the upper surface of the wing than past the lower surface. D) air molecules move more rapidly past the lower surface of the wing than past the upper surface. E) wings are thick enough to create a significant pressure difference between the top and bottom surfaces of the wings because of the different heights of these surfaces.
Triton orbits in the same direction as Neptune's rotation
a. True b. False Indicate whether the statement is true or false
A basketball player jumps to make a basket and remains in the air for a moment. A sportscaster then remarks that she has "defied gravity." Which of the following accurately describes the situation?
A) The player did stay in the air in spite of the Law of Gravitation, but a single counter-observation is not enough to warrant revisiting a theory that usually works. B) The player produced enough force with her legs to accelerate upward and remains above ground only until the acceleration of gravity brought her back down. C) The player can "defy gravity" because the Universal Law of Gravitation makes an exception for basketball players. D) The player has defied gravity, so scientists must go back into the lab to refine their theory.