X
Other applications: The art of rope-dancing; loading a
bandy, when the heaviest goods should be at the bottom.
CHAPTER II.
Equilibrium stand notion of solid bodies.
109–129
§ 29. 1) Both rest and motion are either absolute or rela
tive. Absolute rest, means the absence of any motion. There
is no such condition, for even the sun rotates about an unknown
central sun. Relative (or apparent) rest is a condition, accord
ing to which a body in reference to surrounding objects is with
out motion, e.g. the passenger in a carriage is in a state of rela
tive rest with respect to his carriage. Our houses are in a state
of apparent rest, but they are in incessant motion with respect
to the sun. As we know no fixed point in the universe, the idea
of absolute-motion cannot also be realized and we know only
of relative motion, e.g. a carriage with respect to the trees and
fields on both sides of the way.
§ 30. 2) That which causes, a body either to
move or to stop is called force, in the first case it is called power, in the
second resistance. The different kinds of motion are (1) uni
form (2) accelerated and (3) retarded motion.
The only uniform motion, of which we know is the rotation
of our earth round its axis; accelerated motion we see in a
falling body and retarded motion will be caused by throwing a
stone perpendicularly upwards. 109.
