The number of houses on fire in a metropolitan area. It’s generally around zero. Whenever the number of fires goes up, firemen show up and reduce the number until it’s close to zero again. Separately, if there is a lot of fire, a lot of things might burn down, but then the fire burns itself out.
A very heavy rock. Because it’s heavy, it doesn’t tend to change.
Salt levels in human blood. If it gets too low, human eats more salt. If it gets too high, liver gets rid of it.
The second one is interesting to me because if you increase weight by caking it in mud, the mud will break/fall/rub off, and the rock will return to its previous weight. But if you break off a piece, it will generally not return to its previous weight. Maybe a version of this that returns to equilibrium from both directions is a car? If you break a reasonable number of pieces off or put wear on the tires or burn some gas or oil, it will return to its ‘equilibrium’ weight via maintenance?
The number of houses on fire in a metropolitan area. It’s generally around zero. Whenever the number of fires goes up, firemen show up and reduce the number until it’s close to zero again. Separately, if there is a lot of fire, a lot of things might burn down, but then the fire burns itself out.
A very heavy rock. Because it’s heavy, it doesn’t tend to change.
Salt levels in human blood. If it gets too low, human eats more salt. If it gets too high, liver gets rid of it.
The second one is interesting to me because if you increase weight by caking it in mud, the mud will break/fall/rub off, and the rock will return to its previous weight. But if you break off a piece, it will generally not return to its previous weight. Maybe a version of this that returns to equilibrium from both directions is a car? If you break a reasonable number of pieces off or put wear on the tires or burn some gas or oil, it will return to its ‘equilibrium’ weight via maintenance?
I particularly like the first one. Highly relevant to current events in California, at multiple timescales.