4. Inertia is a property of matter which
keeps an object in motion until it is
stopped by a force. Or keeps it still until a
force is acted upon it and makes it
move.
5. Friction is the force resisting objects from
going on forever.
6. Simple machines are small and very
simple. They are made to make work easier.
They are also used to make compound
machines, which include two or more simple
machines.