Pushing a baby on a swing is easier than pushing an adult on the same swing.

Water spills from a glass carried by someone who is walking steadily and suddenly stops short.

When thrown with the same force, a soccer ball accelerates more than a bowling ball.

A magician pulls a tablecloth out from under a dish on a table without disturbing the dish.

A rocket launches into space, pushing fuel exhaust in one direction and the rocket in the opposite direction.

A book rests on top of a shelf and does not move until a student accidentally knocks it off.