The physical answer does not understand, if the assumption does not change, then the pressure should

The key reason for the increase in pressure is that there is a section of the glass tube on the left that is horizontal with mercury.

It can be analyzed like this:

Before water injection, the pressure at both ends of the bottom of the U-tube is balanced, the pressure at the right end increases after the right side is injected with water, the left side remains unchanged, and the mercury column on the right side must move to the left until the balance is reached again.

In the process of rightward shifting, the pressure of the air column in b increases, and the upper mercury column moves up, resulting in a decrease in H2, which decreases the pressure in the upper part of the air column and expands the volume of the air column until the equilibrium is re-reached.

In fact, no matter what liquid is added on the right side, H2 will decrease, and the pressure in the air column will decrease.

So under what circumstances can the pressure of the air column increase?

To increase the pressure of the air column, H2 must be increased, and some mercury can be extracted from the right side, not too much, when the mercury on the left side enters the vertical glass tube, the pressure of the air column will reach the maximum.

If there is no horizontal glass tube, injecting or extracting on the right side will only change the position of the air column, but will not change the pressure of the air column.

Select A, when mercury is added on the right side, the pressure on the right side increases, and the pressure difference between the left and right sides should be equal, so B will move up, so that H2 will decrease, and the corresponding pressure in B will decrease, according to P1V1=P2V2 The volume in B increases, and the height will rise!

The pressure increases, the contact area remains the same, and the pressure becomes larger p=f s

The pressure does not change, the contact area becomes smaller, and the pressure becomes larger.

Because the fill becomes larger and unchanged.

The first empty, p=mg s, m becomes larger, so p becomes larger.

The 2nd empty, p= gh, becomes smaller, so p becomes smaller.

Using the formula pressure is equal to the density of the depth of the liquid constant g

<> known, the magnitude and direction of gravity do not change when the ball is in any position.

At each position, the direction of the tension force is known (along the direction of the rope) and the direction of the pressure is known (the normal direction).

Moving slowly means that the forces on the nucleus ball are balanced, and at any given moment, the three forces on the ball form a closed triangle.

As shown in the figure, at any moment in the triangle, the direction of the three sides and the size of one side are known, the size of the other two sides can be determined, obviously, at each moment, the size of the pressure is the length of the radius, that is, the pressure is constant.

It seems that your physical water is still very good, and I don't have a pen on the spine, so I'll remind you that the two corners are not the same, but the two corners Don't be fooled by the diagram.