Surface tension

 

 

Another factor we wanted to observe was how the surface tension of the fluid affected result. Since it is very difficult to set up a controlled experiment where only the surface tension changes and neither the density or viscosity change, we decided it would be best to add soap to water, in little quantities. This way the density and the viscosity are nearly identical to the ones of water, yet the surface tension drastically changes. The collected data is plotted bellow:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

    Graph 4: First measurements.

 

 

Graph 5: Second measurements.

 

We expected to see a linearity in this setup, yet we see a reciprocal dependency. We quickly came to understand that these graphs aren’t a dependency on surface tension, per se. In fact they are a collective dependency of a pre calculated dependency of both surface tension and mole ratio. The function for soapy water tension is better explained by the detailed experiment on surface tension by Science and Technology. For further reading check the refrences. [10]

 

Notable, whilst it is somewhat possible that Graph:5 could be linear, the fourth point makes it unlikely. For a better understanding as to why it shouldn’t be linear check [10] and their references as well.