Gravity.
Not quite.
What cause water to fluctuate in a toilet is a lot more complex then saying gravity.
What normally causes the water level to rise and fall is
1- Negitive pressure
2 - positive pressure
3- Back siphonage
4- The most common is oscillation (wind effect) as the wind goes down the vent terminal.
Negative pressure is when a toilet is flushed on an upper level it draws water from the toilet from the lower floors do to improper venting or a blocked vent. Sylvan, Licensed Master plumber
either bend the arm of the float so it is partially submerged or adjust it with the screw that is attached to the float armature
either bend the arm of the float so it is partially submerged or adjust it with the screw that is attached to the float armature
Assuming you have a regular tank toilet with a ball float and rubber flap and that the water is turned on and the tank is filling, the most common cause of a toilet not flushing is a broken or detached chain that runs from the handle lever to te rubber flap that keeps the water in the tank.
The name of the float mechanism in a toilet is called a ball and cock.
There can be a large number of reasons why it doesn't float. Maybe its not attached properly.
Adjust the flushometer / Fill valve / flapper
The fill valve is not opening. If the valve is a post in the corner of the tank and the float slides up and down on it, there is a washer in the top of it that becomes stiff or plugged and does not let water in.
bananas float with or without skin
If you have a copper float ball that will do it
What causes it to sink or float is the density. The density of water is 1.0. If the object's density is more 1.0 then it sinks, but if the object's density is less then 1.0 then the object will float.
Lack of gravity.
displacement