Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

Using a Lucite or Kundt tube, this quantity can be determined experimentally by examining the sequence of Lissajous curves as the measuring apparatus is moved. The Prandtl-Glauert transformation breaks down at this value as it predicts an object at it would experience infinite pressure. It's often derived as the square root of the adiabatic constant times gas constant times Kelvin temperature over molecular weight, which is why it is commonly approximated for the atmosphere as (*) 331.45 plus 0.61 times Celsius temperature. Often determined in physics labs with a resonance tube or tuning fork, the shock waves formed when this quantity is exceeded give rise to a sonic boom. For 10 points, name this quantity equal to Mach 1, the speed at which acoustic waves travel in a given medium.
Science