The force exerted by air molecules is something that we take for granted every day, but it is a surprisingly powerful force with equally surprising applications. For example, a vacuum cleaner “sucks” dirt in by creating a partial vacuum that allows the air outside the vacuum cleaner to push dirt into it. Similar reasoning can be used to create a vacuum cannon that relies on air pressure to eject a projectile at great (even supersonic) velocity. The following video from the Sixty Symbols Youtube channel illustrates this and provides further technical details.
If you’re interested in learning more about vacuums, Sixty Symbols has a follow up video that reveals their surprising quantum mechanical nature. You may be surprised to learn that a complete vacuum cannot really exist and that empty space actually contains energy. The conversational nature of the video doesn’t allow for a rigorous treatment of the subject, but instead offers an enticing glimpse into the exciting world that research scientists get to explore.