- Sir Isaac Newton understood that an object will change its motion
only if it is acted upon by a force. Otherwise, its motion will be
unchanged. If it is moving, it will continue to move in the same
direction. And if it is standing still, it will remain still. An object
in motion continues in motion and an object at rest remains at rest
unless acted upon by a force.
This is called inertia. Inertia is simply the scientific term
for matter's property of continuing its motion (or lack of motion) until
acted on by some force. This property of inertia is what is described in
Newton's First Law of Motion. The famous trick in which a tablecloth is
pulled off a table, leaving all the dishes, silver, and glasses in place,
works exactly the same way. When the `magician' snaps the tablecloth
away, all the dishes are at rest.
Because of Newton's First Law of Motion, all the items on the
table tend to remain at rest. The rapidly moving tablecloth doesn't
produce enough force to move the dishes very much, and so they stay on
the table. (To do this trick you have to be very skilled.)
|
