Book 26, Question 61
Why does a paper clip hold papers together?
A paper clip is a piece of bent wire in a loop within a loop.
When you slide it over paper, the wire bends slightly apart and then springs back, squeezing the sheets. The metal is springy but not too stiff. The common Gem-style clip, with two loops, was made around the 1890s. It is a simple machine that uses spring force.