A high pressure question in the third year of junior high school, ask the master to answer

d, however, there is a problem with this question, that is, it does not show that the two objects A and B are of the same material, and if it is not explained, there is no solution to this problem. We see him as the same material.

Parse. The two objects A and B are of the same material, and the solid uniform cube A and B of the same mass are placed on the horizontal table respectively, if a certain thickness is cut off in the horizontal direction. Explain that after cutting, the two objects of A and B are the same as g.

The contact area between A and the ground is larger than B, according to the formula p f s, when f g, the smaller the area s p is, the larger it is.

The contact area between A and the ground is larger than that of B, and the two objects of A and B are of the same material, and the blocks of the same material are made according to the volume formula V sh, when V is constant, the larger S is, the smaller h required.

Actually, I think this question is too skimming.

Or am I not able to understand?

Actually, I think I choose B

Actually, I think after reading the question, you will know that you will choose B.

Because the pressure is the same, A should be higher, the bottom area is larger, if A is cut to the same height as B, then the mass of A decreases, the bottom area remains the same, the pressure decreases, and B does not change, so "B, P A P B, H A H B".

b f=ps p A p B s is the base area, s A s B ; It can also be illustrated on the diagram! fA=fBB=mgm=density sh Push out HA, HB.

Option B for the following reasons:

p=f s=g s f is the same, s A s B, so p A P B.

The second question can be solved by a special method If you don't cut B, in order to make the pressure of A and B on the ground the same, A must be cut off a certain thickness in the horizontal direction, so h A h B.

If you don't understand B yet, it's easier to understand with a formula, so let's try it.

Pick B. Because the pressure of A and B on the ground is the same, and the contact surface between A and the ground is greater than the contact surface between B and the ground. According to the formula of the pressure in physics, it can be concluded that p A is greater than p B.

In the horizontal direction, no matter how you cut H, A is greater than or equal to HB.

And only A and B are equal if they are not cut to A and B, so h plus "h B".

The answer is A

The plastic will only fall when the pressure up and down is equal according to the liquid pressure formula p= gh

When the pressure is equilibrium Liquid g (h + 1) = water gh - > liquid * 1 = ( water - liquid) h - > liquid water.

As we know from p= gh, the pressure generated by the liquid on the bottom of the container is related to the density of the liquid and the depth of the liquid. To do this, we can use a cylinder of the same depth as the bottom of the container to find the pressure of the liquid. At this point, p=g s.

Convert the volume of the table to the volume of a cylinder of equal height, i.e., (1 3) (r 2+rr+r 2)h=v=sh, then the bottom area of the cylinder is s=(1 3) (r 2+rr+r 2). Note: This formula will be learned in high school.

Because, when water, kerosene and mercury of the same quality are injected into the original container, the height of the liquid level is: h kerosene "h water" h mercury. So the radius of the upper circle of their round table is:

r mercury >r water" r kerosene. Again, their r is the same, so the circular area of their contour cylinders is: s mercury s kerosene.

Since p=g s and g are equal, p kerosene > p water > p mercury. i.e., in the original container, p kerosene " p water " p mercury.

Since the pressure of them on the bottom of the container in the original container n=ps, and s is the same, n kerosene " n water " n mercury.

When a 100g weight is put in, p=g s, and g is the same, s is greater than the bottom area of the cylindrical water column, so the pressure generated by the weight is less than the pressure generated by water. The pressure on the bottom of the container produced by the weights obtained by n=ps is less than the pressure exerted by the water on the bottom of the container.

From the above analysis, it can be seen that option A is right.

It's a lot of analysis!

The formula for calculating the round table will be learned in high school. However, it can also be understood by the loose cut-and-patch method: see Fig.

The recess in the middle of the two bottles are supplemented with water and brine respectively, so that they all become cylinders, because the volume of the supplement is the same and the density of the salt water is large, so the quality of the salt water is large, so the total mass of the salt water is larger than the total mass of water, because the bottom surface of the two bottles is the same, so the pressure after the cylinder is made up is the salt water, so the original pressure is also the salt water (the pressure before and after the cylinder is the same).

The meaning of the mending method is to treat the blank part of the bottle as if it is filled with their respective liquids, and the two cups are exactly the same so the volume is the same, the density of the brine is greater than the natural mass, and the pressure on the bottom of the bottle is also greater.

What kind of cutting method, I don't wait, but I know that choose B because the quality of the two is the same, so the density is large and the volume is large. Obviously, the density of brine is greater than that of water, so the volume of brine is larger. Because the bottle is fixed, B's liquid level is higher than A's.

Because the pressure is related to the depth, the pressure at the bottom of B is stronger than the pressure at the bottom of A, so p2 p1

If the volume above a piece of land is v=sh, the mass is pv=psh, and the gravity is pshg, then the ground pressure is pshg s=phg

Because p copper, p iron, p aluminum, so the pressure p copper, p iron, p aluminum.

Three metal blocks, available p=gh

So p copper, p iron, p aluminum.

By density, the greater the density, the greater the pressure, I don't remember their density, in short, by density.

1) When the depth of the glass cylinder immersed in water is meters, the pressure of the water on the plastic sheet p= water gh water = 1000kg m3 10n kg If you pour water slowly into the glass cylinder until the water surface inside and outside the cylinder is the same height, the plastic sheet will sink when the water surface in the cylinder is high. 3) If a liquid to be measured is slowly poured into the glass cylinder, the plastic sheet will begin to fall off when the liquid level in the cylinder reaches a meter height. Then the density of the liquid is determined by p = liquid gh liquid, resulting liquid = p (gh liquid) = 2100 pa (10n kg

Thin-walled, for the requirement to be true, the object must float in water, and it doesn't matter whether it floats in alcohol or not, and the density range can be known with this. The mass range can be obtained from the density and volume.

The pressure of the liquid in the container to the bottom of each container is equal, then ha=hb, after the ball is removed, the remaining liquid level in the two containers is the same height, then ha'=hb', then ha-ha'=hb'-hb'

So sa (ha-ha').

Select DItem.

First of all, the stressed area is reduced to half of the original area.

Calculate the minimum volume of the cylinder. i.e. 2r = sqrt (2) ab assumes ab = 2.

Then h=4,r=sqrt(2) s=2 m= v=8 the mass of the excavated part m= v=6

The calculator calculates or estimates that the mass is reduced by less than 50%.

So at this point p1 is less than p2.

In the calculation, we use the minimum volume of the cylinder to perform the boundary calculation. When the bottom area of the cylinder increases infinitely, the value m will always be less than s s, so p2 will always be greater than p1

According to the pressure formula, the pressure is related to the force and the force surface, and the mass and ground area of B are set up, corresponding to A. Using the formula, the relationship between p1 and p2 will come out.