Screws (Simple Machines)

"Readers learn how this simple machine makes it easier to keep objects locked together. By the end of the book, readers know the difference between complex and simple machines and how screws are used in everyday life to make work easier."--Publisher's website Tools and machines -- A kind of ramp -- Parts of a screw -- Spinning circles -- Thread power -- Pitch -- Screws and bolts -- In complex machines -- Screws everywhere. Presents A Look At Screws, Explaining How These Simple Machines Work And Describing Some Common Examples That Have Been Used Throughout History.--