"a negative and a positive make a negative:"
https://www.mathsisfun.com/multiplying-negatives.html
Negative Mass
"something called “exotic” matter (which falls up, rather than down)"
https://mkaku.org/home/articles/the-physics-of-time-travel/
"Sound has negative mass, and all around you it's drifting up, up and away — albeit very slowly."
https://www.livescience.com/63305-sound-waves-negative-gravity-mass.html
"The speed at which steam rises can vary based on certain factors but it can be approximately considered as 1.96 m/s"
https://brainly.com/question/39083685