Due to the existence of atmospheric pressure, paper will be "supported" upward by atmospheric pressure, so neither water nor paper will fall down. When the bottle is filled with water, there is no air in it, that is, there is no atmospheric pressure in the bottle, only the pressure of water.
Extended data:
The steps of force analysis are as follows:
1, define the research object.
Before the stress analysis, it is necessary to find out the stressed object. We often say "isolation method" and "whole method", which refer to whether the stressed object is a single object or a whole composed of multiple objects. For connectors, it is often necessary to change the research object several times to solve the problem when analyzing the force.
Sometimes, it is difficult to find the force by choosing the stressed object as the research object. At this time, we can transfer the object, select the stressed object of this force as the research object, work out its reaction force, and then work out this force according to Newton's third law.
2, orderly analysis of pressure
It is necessary to form the habit of force analysis according to certain steps to avoid force leakage or force application. Generally, it is divided into three steps: first, analyze gravity, then find out the object in contact with the research object, analyze the contact force, such as elasticity and friction, and finally analyze the electric field force and magnetic field force.