## Nano-technology – friction on the nano scale
Presenter: Andy Jackson Va. SOL:
Safety Considerations
The data you will collect is the normal force and the frictional force. The data collected is not in Newtons, but is in a unitless form that is directly proportional to the force in Newtons (or nano-Newtons). The AFM tip will scan back and forth a few times while the contact force remains constant. As the AFM tip scans it will be tilted by the frictional force. The amount of tilt is directly proportional to the force of friction. Data for the force of friction will be numeric values that when graphed look something like this: How do I get the force of friction from this?Half the difference between the values of the upper plateaus and the lower plateaus is the force of friction. - Use Logger-Pro features to determine the average value of each plateau and the uncertainty of this value (standard deviation of the mean)
- Find the difference between the values of adjacent plateaus. The uncertainty in this value is the sum of the uncertainties from #1.
- Average the several different values you got for your run and use the average uncertainty from step #2 to represent the uncertainty in your final value of frictional force.
Create an organized table to present this information. Other groups will be collecting the same data but with a different amount of force pressing the tip against the sample. Collect the data from all the groups to complete the table below.
Plot a graph of Frictional force Vs Normal Force. Include error bars for Frictional force. What does the shape of the graph tell you about the coefficient of friction on the nano-scale as compared to the coefficient of friction on the macro-scale? .
## Teacher Tips Regarding LabThis has been a possibility for my students through a partnership between myself and Dr. Scott Paulson at James Madison University. This has been a great opportunity for my students to experience aspects of physics that I believe will be a rich field during their life time. My school’s top science students get a chance to be wowed and taught for a couple of days by a JMU physics professor. It is my hope that the AFM and nano manipulator are a source of great interest that may attract some students to the fields of physics or engineering. Most major colleges and universities have Atomic Force Microscopes and hopefully are looking for chances to partner with high schools. |

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