Why Do Tape Dispensers Have Serrated Teeth?
When sealing an envelope or wrapping a package, you unroll a length of clear tape from its dispenser. You stretch it taut and press it against the ro…
Why Do Trash Cans Have Foot Pedals?
When clearing a table or emptying a bin, you head to the trash can in the kitchen or office. Near the base, a flat pedal protrudes, designed for foot contact. This pedal forms part of a linked system…
Why Do Batteries Have a Bump on One End?
You slide open the back cover of a remote control or flashlight, revealing the battery compartment. You grab a few AA batteries from the drawer and i…
Why Do Sinks Have Overflow Holes?
Why Do Sinks Have Overflow Holes? When washing hands or dishes, a sink basin collects water from the faucet above. The water stays in the basin until released through the drain at the bottom. Look cl…
Why Do Hammers Have a Claw on One Side?
When hanging a picture or fixing a loose board, you pick up a hammer. Its solid metal head delivers the force needed to drive a nail into place. A cl…
Why Do Pens Have Pocket Clips?
Every day, people pick up a pen to jot down a phone number, sign a form, or sketch a reminder. Once the task is done, the pen slips easily into a shirt pocket, notebook edge, or planner cover. A deta…
