What vibration produces the sound of blowing on an empty bottle

It is air. When blowing into the bottle, the air is constrained by the bottle and forms a cyclone near the bottle mouth, resulting in vibration and sound caused by air collision. Like thunder, it is caused by air collision

Seven identical bottles filled with water of different heights can make different sounds by knocking them. Why? Write a paper on the above questions, as long as the conclusion is OK, hundreds of words must be The following people speak very well, but can you give me a systematic answer, about hundreds of words, thank you. PS: I'm a student of grade one. Please don't give me those things I learned in high school

It is the vibration of the bottle wall that makes the sound. It is the different tone, which is caused by the different frequency of the vibration of the outer wall of the bottle due to the different amount of water. It is not the echo! When knocking, the sound is made by the vibration of the cup. The less water in the cup, the greater the vibration and the higher the tone. The natural frequency of water is the same, if it is the same water, but because the water is

The bottle held vertically in the hand does not slide down, logically, because the static friction between the hand and the bottle is equal to the gravity of the bottle. However, if the force holding the bottle increases and the pressure increases, the static friction will also increase, but the gravity of the bottle will not change. At this time, the static friction between the hand and the bottle is not greater than the gravity of the bottle? But that's wrong. Why? If the static friction force is greater than gravity, they are in the opposite direction. Will the bottle move upward? Or is gravity equivalent to a pressure at this time, so that the static friction increases, the gravity increases, and the static friction also increases? Does static friction and pressure have nothing to do with roughness?

You put your hands together and squeeze them together, but don't move. Do you feel friction? No, right. But are you moving? I feel heat and friction. If it is not obvious, I might as well put a piece of sandpaper between my hands. The key to whether friction occurs is whether there is a trend of relative motion. If not, there will be no friction

A sound source is vibrating, but people can't hear the sound. On the possible causes of this phenomenon

The frequency of sounds that people can hear is limited, as if it is 20-2000
It is possible that the vibration frequency of the sound source is not in this range, the latter is too far away, and there may be no transmission medium in vacuum

A sound source is vibrating, but people can't hear the sound. What are the possible reasons for this phenomenon Answer carefully and offer a reward

First, people are deaf

A sound source is vibrating, but human ears can't hear the sound. What are the possible reasons? Answer at least three

(1) The human ear can not hear the sound. It may be that the amplitude of the sound source is too small or too far away from the voice body; (2) Sound transmission requires a medium, so when there is no medium to transmit sound between the sound source and the human ear, people will not hear the sound; (3) When the frequency of sound is higher than 20000hz or lower than 20Hz, this frequency range

What vibration produces the sound of blowing on an empty bottle