Thinking questions about physical acoustic phenomena, experimental questions about physical acoustic

A strikes at one end, and B is heard exactly twice at one point, i.e., the sound that travels from the iron and from the air.

The human ear needs to distinguish between acoustic and echoic sounds.

So the two sounds are separated by seconds.

i.e. ab 340 - ab 5200=

The solution is ab=c exactly three times at one point, i.e., the sound that travels from iron, water, and air.

The time difference between iron and water transmission is sufficient.

ac/1500-ac/5200=

Solution: ac=

Parse first. The first is to hear the sound waves in the iron first, and then the sound waves in the air (the sound waves of water and iron cannot be distinguished because the interval is too small and there are limitations).

In the second case, in order, there is the sound of iron, the sound of water (which can be distinguished from the sound of iron), and the sound of air.

Solve again. Case 1, s 340-s 5200 = solution s = m.

The case is solved with s = m.

The first sound from the iron can be heard, and B only hears two sounds, because the time difference between iron and water, and water and gas is small, so the water is masked x 340-x 5200=

x=8840 243c, can hear three sounds, as long as the time difference between iron and water is y 1500-y 5200= y=7800 37

Ask the question: How is sound produced?

Conjecture or hypothesis: collision, vibration.

Equipment: tuning fork, hammer, rubber band.

Design experiment: Knock on the tuning fork: make a sound, vibrate.

Pull the rubber band: make a sound, vibrate.

Conclusion: Sound is produced by the vibration of an object.

Answer: (1) Analyze the speed of sound in the air for 340 seconds, first of all, 1000km should be converted into 1000000m

1000000 340=2941 seconds = hoursSo, it takes about hours to travel from Beijing to Shanghai.

2) The speed of the train is 100km s, the distance is 1000km, 1000 100=10 hours.

So the train takes 10 hours to get from Beijing to Shanghai.

3) The speed of a jumbo jet is 600km h, the distance is 1000km, and 1000 600= hours.

So it takes about an hour for a jumbo jet to travel from Beijing to Shanghai.

If the air temperature is 15°C, then the speed of sound is 340m s=1224000m h

The supersonic airliner flies a distance of at least 1224km per hour.

The speed of the sound is about to be 40*

Assuming that the velocity of the shell is v, then it passes to the destination, so the distance between the two places is.

And from the beginning of the shooting, the sound of the cannon is heard, but this is the time when the cannon arrives, that is to say, the cannon ** starts to the sound only passes, so the ** point is the distance from the destination to the person = 340m

Therefore, the velocity of the shell v=850m s was solved