Physics Experiment How to measure the speed of sound, how to measure the speed of sound in water Un

Instruments and equipment].

Bangzi, stopwatch or watch, tape measure.

Experimental Method] Echoes can often be heard when singing or shouting in front of high walls or in valleys, and the echoes are clearest and loudest in the morning, so this experiment is best carried out in the morning. First of all, choose a suitable experimental site, such as a high wall, with a flat and empty front of the high wall. The experimenter stands at a distance of r from the high wall and beats the bangs at uniform intervals.

When the first bang sound is heard and the second bang sound is completely overlapped, it means that the time of each bang sound transmitted to the high wall and reflected by the high wall to the experimenter is exactly equal to the time interval t of the bang. Therefore, the velocity of sound propagation v is v=2r t

1 Stand at a distance of 100 meters or more from the high wall and bang on the bang at regular intervals.

2. Pay attention to the rhythm of the bang, so that the sound of the bangs reflected from the high wall overlaps with the sound of the bangs.

3 One of the students standing next to him will report the number of strokes, and the other students will use a stopwatch or watch to time them at the same time. The time interval t between 20 and 50 strokes was measured, and the time interval t (seconds) of the knock was calculated from the obtained results.

4 Use a tape measure to measure the distance r (m) from the striking point to the high wall.

5 Substituting the obtained data into the formula v=2r t to find the speed of sound vm. Also make a note of the temperature of the air at the time of measurement, as the speed at which sound travels in the air is related to the temperature.

Two classmates are some distance away from each other (not too short, not too long. One shouted, and motioned for another classmate to shout. When the non-shouting person sees the signal to use the stopwatch to mark the time, the sound stops listening. Remeasure the distance and calculate.

You face a wall 20 miles away, you shout, use the stopwatch to calculate how many times to receive an echo, calculate. If it's too late, go farther.

The experimental principle of sound velocity measurement, because ultrasonic waves have the advantages of short wavelength, easy directional emission and easy reflection.

Because ultrasonic waves have the advantages of short wavelength, they are easy to be emitted and reflected. The advantage of measuring the speed of sound in the ultrasonic band is that the wavelength of the ultrasonic wave is short, and the speed of sound can be measured more accurately at short distances.

The emission and reception of ultrasonic waves are generally realized through the mutual conversion of electromagnetic vibration and mechanical vibration, and the most common method is to use the piezoelectric effect and the magnetostrictive effect to achieve. In this experiment, a transducer (probe) made of piezoelectric ceramics is used, which can be used to convert energy between mechanical vibration and alternating voltage in both directions.

Methods for measuring the speed of sound:

Once a sound is generated, it doesn't reach your ears right away, usually after a while. It's hard to understand unless you have this experience yourself.

For example, if you attend a sports day and sit at a distance from the person who fired the gun, you will see the gun smoke first and hear the gunfire later. This is because light travels very fast (about 300,000 kilometers in 1 second) and sound travels much slower (about 340 meters in 1 second).

So you'll see the gun smoke right away, but the sound won't be heard until a little while.

The speed of sound is the speed of propagation of a weak pressure disturbance in a medium, and its magnitude varies depending on the nature and state of the medium. The speed of sound in the air is about 1 m s at 15 standard atmospheres and 340 m.

If you have an idea, I don't know if it's feasible, hehe, you can just take a look.

According to the speed = distance time.

Prepare a 100m long water pipe, which can run water, a sounder (preferably timed), a sound receiver, and a timer (stopwatch, mobile phone, etc

The sounder emits sound on one side of the pipe, the receiver receives it on the other side, and if it can't be received, it is OK to shorten the pipe.

The sound is regular, not every 1s (in order to eliminate interference, the time interval can be appropriately extended), about 30 times, because the received sound should be transmitted from the air, water pipe, water, three media, and the speed should be the air "water pipe" water, all the first two sounds do not, from the third sound to the end of the last sound timing, at this time the sound through the whole distance should be 100m x 30 times = 3000m, the time should be The recorded time - 30 times in the middle of the interval, according to the speed of sound in the sea propagation of the number of degrees is about 1500m per second, all the time obtained should be about 2s, if you can get such a time, I think your experiment should be basically successful, if the time obtained and this time deviation is too large, then the experiment will fail. Hehe.

Good luck!

Electronic timers, underwater horns, underwater microphones, tone generators, etc. The horn sounds, the timer starts, the microphone receives the sound, and the electronic watch stops. Horns and microphones are installed at each end of the 50-metre swimming pool.

Make a master control switch (or button), the equipment is energized, as soon as the switch is turned on, the horn sounds, the watch starts the timing, the sound wave reaches the microphone, and the timing is stopped. The propagation time of sound in the air is about a second at 50 meters, and it will be faster in the water.

In general, light is used to help in the measurement. If a distance is selected (relatively far), light (or smoke) and sound are emitted at the target point at the same time, the timing starts when the light (or smoke) is seen at the predetermined measurement point, and the timing ends when the sound is heard, the time difference is the propagation time of the sound, and the speed of sound is obtained by dividing the known distance by this time.

One of the simplest and most effective ways to measure the speed of sound is to use the basic relationship between the speed of sound v, the vibration frequency and the wavelength, that is, a pair of ultrasonic piezoelectric ceramic transducers with the same structure (transmitter and receiver) are used to convert the sound pressure and voltage during the experiment.

The amplitude and phase of the ultrasonic wave are observed by using an oscilloscope, the wavelength is determined by the amplitude method and the phase method, and the frequency f is directly read out by the oscilloscope.

Resonant frequency: ultrasonic piezoelectric ceramic transducer is the key component of the experiment, each pair of ultrasonic piezoelectric ceramic transducer has its own inherent resonant frequency, when the resonant working frequency of the transducer system is in the resonant state, the ultrasonic power emitted by the transmitter is the largest, is the best working state.

Fundamental quantities in acoustics.

In acoustics, or the characteristics of the sound source and the sound field it produces, or some quantities that play a leading role in certain acoustic phenomena and effects, are the basic quantities in acoustics. Table 1 lists these fundamentals and their interrelationships. Of the first four quantities, sound intensity is the easiest to measure and can be measured very accurately, and the other three can be derived from sound intensity, so it has been mistaken in the past that only sound intensity is the fundamental quantity in acoustics.

The above content refers to: Encyclopedia - Acoustic Measurement.