What is the explanation of Earth's magnetism?
A) Subatomic particles known as magnetic poles reside in the Earth, with one type of magnetic pole residing at Earth's north pole and the other type of magnetic pole residing at Earth's south pole.
B) It is caused by electrically charged material circulating within Earth's hot liquid core.
C) Earth's magnetism a consequence of the world's physics professors all spinning in the same direction.
D) It is caused by a separation of charge within the Earth, with positive static charge residing at one of Earth's poles and negative static charge residing at the other pole.
E) It is caused by charged, or ionized, particles circulating in the air above the solid Earth.
Question 2
A math book and a science book are tied together with a length of string. With the string taut, one book is pushed off the edge of a table. As it falls, the other book is dragged horizontally across the table surface.
With no friction, acceleration of the books is
A) zero.
B) g/2.
C) g.
D) between zero and g.
E) greater than g.
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