# Why Does the Pulley Section Lack a Standing Wave in the String Experiment?

• ghostcloak
In summary, the conversation discusses an experiment involving standing waves on a string. The question is raised as to why there is no standing wave on the segment of the string between the pulley and the mass hanger. It is suggested that the pulley acts as a fixed node and dampens the vibration at that point. Further research is needed to determine if the size of the pulley plays a role in this phenomenon.
ghostcloak
Here's one for you guys. I've done some research and I couldn't find an exact answer to my question...

In the experiment shown here:

http://www.itc.csmd.edu/mth/ahouser/PHY1010/labs/Lab10StandingWaves.pdf

Why is there no standing wave on the segment of the string between the pulley and the mass hanger? I'm guessing it's because the pulley is a fixed node that cannot oscillate? Is there more to it than this?

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Yes I believe that the pulley deadens the vibration at that point. Even though it is at a node, and would continue vibration if the pulley was very very small, I think it is big enough to deaden the string that is wrapping around it.

You are correct in your reasoning that the pulley acts as a fixed node and therefore does not allow for any standing wave to form on the string between the pulley and the mass hanger. This is because standing waves require two fixed nodes at either end of the string in order to form. Without the pulley acting as a fixed node, there would be no stable point for the standing wave to oscillate between.

Additionally, the mass hanger acts as a movable node and is able to oscillate freely, which is essential for the formation of a standing wave. If the string were to be fixed at both ends (pulley and mass hanger), there would be no movement allowed and therefore no standing wave could form.

Another factor to consider is the tension in the string. In order for a standing wave to form, there must be a balance between the tension in the string and the frequency of the wave. The pulley and mass hanger play a role in adjusting the tension in the string, which is necessary for the standing wave to form.

Overall, the combination of a fixed node (pulley) and a movable node (mass hanger) allows for the formation of a standing wave on the string. Without both of these components, a standing wave would not be possible.

## What are standing waves?

Standing waves are a type of wave that is formed when two waves with the same frequency and amplitude travel in opposite directions and interfere with each other. This creates a pattern of nodes and antinodes, where the amplitude of the wave remains constant at certain points while it cancels out at others.

## How are standing waves different from traveling waves?

Traveling waves move through a medium, while standing waves do not. Standing waves are formed due to the interference of two waves, while traveling waves are created by a disturbance in the medium. Additionally, standing waves have a fixed pattern of nodes and antinodes, while traveling waves do not.

## What is the equation for the frequency of a standing wave?

The frequency of a standing wave can be calculated using the equation f = nv/2L, where n is the number of nodes, v is the velocity of the wave, and L is the length of the medium.

## How are standing waves used in real-world applications?

Standing waves have many practical applications, including in musical instruments, microwaves, and medical imaging. In musical instruments, standing waves are responsible for creating specific notes and tones. In microwaves, standing waves are used to evenly distribute the energy and cook food more efficiently. In medical imaging, standing waves are used to create images of internal organs and tissues.

## What factors affect the formation of standing waves?

The formation of standing waves is affected by factors such as the frequency and amplitude of the waves, the properties of the medium, and the boundary conditions of the medium. The length of the medium also plays a role in determining the number of nodes and antinodes that will form in the standing wave pattern.

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