The goal of this activity is for students to identify and predict the effect of string tension, string length, and linear density of a string on the wave velocity through that string. From their investigation of one of these factors students will, as a class, construct a model that shows the relationship between these factors.

In the Preliminary Observations, students will observe a stringed instrument or hollow box with rubber bands across an open side. Students should identify a couple of factors that may influence the wave speed on the strings such as string tension, thickness/weight of string, and string length.

During their investigations, students will determine the relationship between one factor and wave speed. Since groups may be investigating different factors, you will need a class discussion after the investigations to summarize the class’s findings.

We recommended a specific equipment setup in order to narrow the focus of the investigation. However, students should be encouraged to consider other approaches that effectively isolate the variable of interest.


  • Design and perform an investigation.
  • Draw a conclusion from evidence.
  • Identify string tension and mass per unit length as the determining factors of wave speed on a string.
  • Create a model for factors affecting wave speed on a string.