Please design the experiment, measure the atmospheric pressure. Write the required physical quantity and calculate the atmospheric pressure formula There is a straight glass tube with a uniform inner diameter and a length of about 2 meters, a small glass of water, a scale and a plasticine. Please design an experiment to measure the atmospheric pressure, write down the required physical quantities, and calculate the atmospheric pressure formula

Please design the experiment, measure the atmospheric pressure. Write the required physical quantity and calculate the atmospheric pressure formula There is a straight glass tube with a uniform inner diameter and a length of about 2 meters, a small glass of water, a scale and a plasticine. Please design an experiment to measure the atmospheric pressure, write down the required physical quantities, and calculate the atmospheric pressure formula

First, plug one end of the glass tube with putty
Then, insert the glass tube (plug one end up) vertically into the glass of water (do not let out the air in the glass tube). At this time, the air in the glass tube is compressed. Use a scale to measure the following three physical quantities: the length of the air column in the tube D, the height difference between the water surface and the nozzle h, and the length of the glass tube H
If the density of water (ρ) and the local acceleration of gravity (g) are known, the formula is as follows:
1. (atmospheric pressure) P = (air pressure in pipe) PX - ρ × g × (H + D-H)
2. PX / P = H / D (because the inner diameter of glass tube is uniform)
It can be obtained from 1,2
P = [ρ×g×(h+d-H)] / [(H/d）-1]
Where H + D-H is the vertical distance from one end of the interface between air and water surface
Note: after inserting the water, the rubber should not go too deep into the tube. It is better to be flat with one end of the glass tube, because it will affect the accuracy of measurement

(in the experiment of measuring the acceleration of gravity with a simple pendulum, if I is the length of the pendulum and t is the period, then the expression of the acceleration of gravity g =?
thank

According to the period formula of simple pendulum: L / G under t = 2 π * radical
So g = 4 π ^ 2 * L / T ^ 2
For the derivation of the period formula, see

What is the acceleration of gravity? What is the formula? How to find it

The acceleration of an object near the earth's surface under the action of gravity is called the acceleration of gravity, or the acceleration of a free falling body, expressed in G
[Nature]
In this case, the acceleration of gravity decreases significantly with the altitude of the earth, while the acceleration of gravity decreases significantly with the altitude of the earth
The acceleration of gravity at the same height from the ground will also increase with the increase of latitude. Since gravity is a component of gravity, another component of gravity provides the centripetal force needed for the object to move around the earth's axis in a circle. The higher the latitude of the object, the smaller the radius of the circular orbit, and the smaller the centripetal force required, the gravity will increase, The radius of the circular orbit at the north and south poles is 0, and the required centripetal force is 0. Gravity is equal to universal gravitation, and the acceleration of gravity also reaches the maximum
[numerical value]
Since G does not change much with latitude, the standard value of the acceleration of gravity is 9.80665 M / S ^ 2, which is accurately measured at sea level at 45 ° latitude. In solving the problems near the earth's surface, G is usually taken as a constant. In general calculation, G can be taken as 9.80 M / S ^ 2, The value of G increases slightly, for example, g = 9.780 M / S ^ 2 near the equator and 9.832 M / S ^ 2 in the Arctic. The conversion relationship between different units of G is: g = 9.81m/s2 = 981cm / S2 = 32.18ft/s2
Note: the figure shows a gravity acceleration test sheet
The acceleration of gravity on the surface of the moon is about 1.62 m · S-2, which is about one sixth of that of the earth