Chapter 7 Question ○○3

Why is there a lock on the door of a 24-hour convenience store? (Lina Baker, Ebony Johnson) Many convenience stores are open all year round.Why bother putting a lock on the door since they never close it?Of course, there will always be emergencies of one sort or another that force convenience stores to temporarily close.Take, for example, the unprepared evacuation of New Orleans residents after Hurricane Katrina: Obviously, convenience stores that are unstaffed and unlocked are good prey for looters.Even barring these emergencies that might close the doors, there is little benefit to buying unlocked doors at convenience stores.

The vast majority of industrial doors are sold to places that don't need to be open 24 hours a day: places that obviously have reasons to want locks on their doors.So, since most industrial doors are sold with a lock, it must be cheaper to make all the doors to the same pattern.This principle is the same as that all cash machines (even those installed on the side of the highway) have Braille on their keyboards. The following two examples show that sometimes the details of product design seem to have a certain relationship with geometric principles.