Physics Problems About Acoustic Phenomena, Junior High School Physics Tutoring Acoustic Phenomena

You go out with a pen and paper now, and when you hear the sound, you think about what the vibration is, you should be able to think of it!

Playing the violin: The strings vibrate.

Drumming: The drum face vibrates.

Speech: Vocal cord vibration.

The wind is roaring and the air is vibrating.

The horse is barking and the vocal cords vibrate.

The Yellow River is roaring and the water is vibrating.

Speaking - vocal cord vibration; ** sound - horn vibrating; Applause – hands shaking; The sound of the whirring fan - the fan blades vibrate; Dog barking - the dog's vocal cords are vibrating; Cat meow - the cat's vocal cords are vibrating.

Everything is moving now.

The wind is roaring and the air is vibrating.

The horse is barking and the vocal cords vibrate.

The Yellow River is roaring and the water is vibrating.

Drumming The drum face vibrates.

..You are a bad student, as long as there is movement, there is basically vibration (under non-ideal conditions, there is friction, sliding friction, rolling friction, friction is all, friction will inevitably produce vibration), sound is just a reaction to vibration. Got it?

There is also a direct so-called seismic force generated by direct vibration, why? The force acting on the molecules causes the movement of the molecules, and from the macroscopic point we see the vibration of the object.

Hmph, the example I gave is problematic.

True/False. 1.(2 points) On the Moon, there are two astronauts, A and B, and A "yells" at B, but B still can't hear because there is no air on the Moon. (

2.The pitch is determined by the speed of the vibration of the sound source, and the faster the vibration, the higher the tone orange peel. (

3.(2 points) People use decibels to measure the level of noise. (

4.(2 minutes) 30 40 dB is an ideal quiet environment, more than 50 dB will affect sleep and rest. (

5.(2 points) The higher the frequency, the lower the pitch. (

6.(2 points) When bees and butterflies fly, their wings vibrate, and people can hear the buzzing of bees but not the butterflies because the amplitude of the butterfly wings is small. (

7.(2 points) Because all sound sources are vibrating, all vibrating objects are making sounds. (

8.(2 points) All gases, liquids, and solid substances are cracked and can transmit sound. (

9.(2 points) Above 70 decibels will interfere with the conversation and affect work efficiency. (

10.(2 points) For the same tuning fork, tapping the tuning fork with a hammer is higher than tapping the tuning fork lightly

11.The lower the frequency, the lower the loudness ( ).

From the point of view of physics, noise refers to the sound emitted when the sound emitter vibrates irregularly, and from the perspective of environmental protection, all the sounds that affect people's normal work, rest, study and life belong to noise

So the answer is: irregular vibration

Draw a picture first, and when the sound of the plane above your head reaches your ears, the plane is already flying ahead! If the plane is off the ground, the sound source is also the same height from the ground! and time equality is set to t, v sound = h t

v machine = tan30'*h/t

v machine = tan30'*V sound.

s=2*tan30'*v sound.

Set the velocity to V, from the top of the head to 60'Duration tThe equation can be established: vt 340t = tan30'。Solve v in multiplication by 2

Suppose the altitude of the aircraft above the ground is h, the sound velocity is v1 (generally 340m per second), and the aircraft speed is v2, and the distance of the aircraft in this process is, tan60'=h sFrom this, it is 2 minutes away from s1=v2*120,

Compared to the speed at which time travels through the air, light travels through the air at a very fast rate, so the time it takes for Xiao Ming to see the plane can be ignored.

Pythagorean answer: This is an RT triangle, and the short straight side is the distance traveled by the aircraft, set xthen the hypotenuse is 2x (the short side of the 60-degree right angle is 1 2 of the hypotenuse).

The long straight edge is the speed of the sound. According to the Pythagorean theorem, the long straight side = (root number) hypotenuse square - short side squared = (root number) 2x squared - x squared = (root number) 3x

So the velocity of this plane is x (root number) 3x = (root number 3) 3 of the speed of sound

Let the propagation velocity of sound in the air be ts, because the sound is heard twice, the first time is through the steel, and the second time is transmitted through the air, then the propagation time in the steel is (t-20)s, so the equation is :

340*t＝5000*(t-2)

Solution t 500 233

So the length of the railway is s=v*t

Sorry, my answer was so stupid.

Suppose the length of the railway is x, and B hears two sounds, first through steel and then through air. The time difference between the two propagations is 2s. So.

x 5000 + 2 = x 340, find the value of x is the length of the railway. Please also ask the landlord to figure out the answer himself.,Thank you for adopting.。

It's simple.

This section of the railway is long

then s 340-s 5000 = 2

Find s=

Solution: Let this section of the railway be x meters long.

x/340-x/5000=2

x is approximately equal to. A: This section of the railway is meters long.