Physics in Everyday Life

How do zippers work?

By: Sai Piyush Pathak - Researcher

Zippers are a simple yet brilliant invention that use basic physics to function. They rely on mechanical interlocking to keep two pieces of fabric securely fastened. The teeth of a zipper are like tiny hooks that connect with each other as you pull the slider.

The slider is the key part, it moves up or down the chain of teeth. Inside the slider is a wedge shaped groove that pushes the teeth together when you pull it upward, locking them in place. When you pull the slider downward, it separates the teeth, allowing the zipper to open.

What keeps a zipper secure is friction. Once the teeth interlock, friction between them prevents the zipper from sliding apart on its own. This ensures the fabric stays closed even under tension.

Zippers are also an excellent example of force distribution. The pressure you apply to the slider spreads evenly along the chain, making it easy to zip up or down. This clever design is why zippers are strong yet effortless to use.