Real-time measurements of static and kinetic friction: A computer-aided experiment

Abstract

We performed real-time measurements of static and kinetic frictions. A simple bridge type connection of strain gauges (variable resistors) is used as sensor to measure frictional force. The output voltage of the sensor is sent to the computer via a data acquisition card (National Instrument; DAQ card) and a program written in LabVIEW converts these voltage readings to force measurements. A good distinction between static and kinetic frictions can be easily observed from the measured data (which cannot be shown by using the usual friction demonstrations; i.e., inclined plane). We believe that the experiment is suitable for undergraduate (or high school) level and can offer to students an excellent training on the concept of friction.