# Calculating the speed of longitudinal wave

• bolzano95
In summary, the conversation was about understanding the speed of longitudinal waves. The professor explained that when a force is applied to one end of a slinky, that part of the slinky will start moving with velocity v. However, the velocity is not constant. The equations for transverse waves also apply to this situation. The main question was about the wavefront at the start of a wave packet, as well as understanding the continuously propagating case. The student eventually understood that the change in momentum from the applied force is what determines the velocity of the wave.
bolzano95

## Homework Statement

I didn't quite understand my professor when he defined the speed of longitudinal wave.
Lets say I have a slinky and on one side we act with a force F along the slinky. Well, he said that this part then starts to move with velocity v.
But how? v isn't constant...

## The Attempt at a Solution

bolzano95 said:
I didn't quite understand my professor when he defined the speed of longitudinal wave.
Lets say I have a slinky and on one side we act with a force F along the slinky. Well, he said that this part then starts to move with velocity v.
But how? v isn't constant...
Have you seen animations or videos of this situation? As with transverse waves, the spring constant and the linear mass density enter into the equations, right?

Is your main question about the wavefront at the start of a wave packet, or do you have problems with the continuously propagating case too?

Of course! I totally get it now :)
I had a problem with the force and the velocity (constant force- velocity is changing). I realized because there is a force acting on the medium and therefore there is a change is momentum. And from this change of momentum you take the velocity, right?

## 1. How is the speed of a longitudinal wave calculated?

The speed of a longitudinal wave can be calculated by multiplying the wavelength of the wave by its frequency. This equation is represented as v = λ * f, where v is the speed in meters per second, λ is the wavelength in meters, and f is the frequency in hertz.

## 2. What factors affect the speed of a longitudinal wave?

The speed of a longitudinal wave can be affected by the medium through which it travels, the temperature of the medium, and the elasticity of the medium. In general, waves travel faster in denser and more elastic materials, and at higher temperatures.

## 3. Can the speed of a longitudinal wave change?

Yes, the speed of a longitudinal wave can change if it travels through a different medium. Each medium has its own specific properties that can affect the speed of a wave traveling through it.

## 4. How does the speed of a longitudinal wave compare to the speed of a transverse wave?

The speed of a longitudinal wave is usually slower than the speed of a transverse wave in the same medium. This is because longitudinal waves require particles in the medium to vibrate in the same direction as the wave is traveling, which can be slower than the transverse motion of particles in a transverse wave.

## 5. What is the significance of calculating the speed of a longitudinal wave?

Calculating the speed of a longitudinal wave is important because it helps us understand how energy is transferred through different mediums. It also allows us to predict the behavior of waves in different situations and can be used to measure important properties of materials, such as elasticity and density.

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