Astronauts, in satellites orbiting Earth, feel weightless. Are they really weightless?
A) Yes, because the centrifugal force due to their circular motion balances the force of gravity.
B) Yes, because they are not in Earth's gravitational field.
C) Yes, because they are "falling" around Earth.
D) No, because the gravitational force is pulling downward on them.
E) No, because the centrifugal force is pulling outward on them.
D
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the greater average kinetic energy per molecule,
A. The quantity is greater for gas A. B. The quantity is greater for gas B. C. The quantity is the same for both gases. D. One does not know enough to compare the quantities.
By locating the north celestial pole (NCP) in the sky, how can you determine your latitude?
A) The altitude of the NCP is the same as your latitude. B) The altitude of the NCP is your angular distance from the North Pole. C) The azimuth of the NCP is the same as your latitude. D) The azimuth of the NCP is the angular distance from the North Pole. E) The altitude of the NCP is the same as your distance from the North Pole.
The most harmful radiations are those that
A) kill living cells. B) damage living cells. C) don't encounter cells.
Two parallel conductors are carrying currents in the opposite direction. The currents are non-zero and not necessarily equal. The magnitude of the magnetic field midway between them is 40 ?T. If one of the currents then has its direction reversed, what is the resulting magnitude of the magnetic field midway between them?
a. a value greater than 40 ?T b. 40 ?T c. a value less than 40 ?T d. It could be any value.