Spring-loaded tools, which release a sharp head at a high speed when you pull the trigger, passed all tests on tempered glass. Only one of the tools failed one of three attempts to break the window.

Frequency and Sound. So obviously, there are a few important pieces to getting glass to break using any kind of sound: A frequency that matches the glass's resonance spot (at least 100 decibels) ...

Around 2:30 p.m., the 1 WTC window washers were rescued by members of the New York City fire department, who broke a window to pull them inside to safety. Subscribe to the Design newsletter.