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

[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?

 

[Tourniquet]

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.

 

[sir-pinski]

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.