2. A screw is a metal object like a nail. It has a
spiral edge around it. It’s used to attach one
thing to another.
3. The screw was invented in 700BC.
Ancient Greece invented the Ancient screw
more then2,000 years ago.
The first screw was a screw pump used for a
king’s garden in ancient Egypt.
Screws are one of the few simple machines
that have exited since ancient times.
With screws people can tighten and grip
things with much more force than they can by
pushing or pulling!
4. A propeller on a boat is a screw that cuts
through water.
If a screw has few thread lines it will cut
materials quickie and deeply.
There are serial deferent types of screws. The
inclined plains are steep or on some.
