# Longitudinal Waves: Compression or Rarefaction at Displacement 0?

• duckandcover
In summary, the displacement of 0 on a (pressure/position) and (displacement/position) graph represents the average of the molecules' movements in that area. This results in a compression or rarefaction, depending on the direction of the displacements. This helps to understand the concept of compression and rarefaction in longitudinal waves.
duckandcover
Why is it that when a longitudinal wave is represented by a (pressure/position) and a (displacement/position) graph does the displacement 0 represent a compression or rarefaction
(maximum or minimum pressure)?

You can think of it as the average of what the molecules are doing there. The compression peaks occur where the molecules are coming together, so the displacements of the molecules are all directed towards that point and they average out to zero. Similarly for rarefaction, except that they are direcected away from that point.

turin said:
You can think of it as the average of what the molecules are doing there. The compression peaks occur where the molecules are coming together, so the displacements of the molecules are all directed towards that point and they average out to zero. Similarly for rarefaction, except that they are direcected away from that point.

thanks that clears it up

## 1. What is a longitudinal wave?

A longitudinal wave is a type of wave in which the particles of the medium vibrate in the same direction as the direction of the wave's motion. This type of wave is also known as a compression wave because the particles are compressed and expanded as the wave passes through them.

## 2. How is compression or rarefaction determined at displacement 0?

Compression or rarefaction at displacement 0 is determined by the position of the particles in the medium when they are at rest. At displacement 0, the particles are neither compressed nor expanded, and are in their equilibrium position. This point is also known as the zero displacement point.

## 3. What is the difference between compression and rarefaction in a longitudinal wave?

Compression is the region of a longitudinal wave where the particles are close together, while rarefaction is the region where the particles are spread apart. This is due to the alternate compression and expansion of the particles as the wave passes through them.

## 4. How does the wavelength of a longitudinal wave affect compression and rarefaction?

The wavelength of a longitudinal wave is the distance between two consecutive points of compression or rarefaction. A shorter wavelength means that the compression and rarefaction regions are closer together, while a longer wavelength means they are farther apart.

## 5. What are some examples of longitudinal waves?

Some examples of longitudinal waves include sound waves, seismic waves (such as P-waves), and pressure waves in fluids. Longitudinal waves can also be observed in springs, where the particles of the medium (the coils) vibrate back and forth in the same direction as the wave's motion.

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