Teacher guide featuring 15 labs designed for Advanced Placement Physics 1.
Students use a motion sensor and a force sensor to determine the static and kinetic friction coefficients between two contacting surfaces.
How can the coefficients of kinetic and static friction between two surfaces be determined? Experimentally determine the static and kinetic friction coefficients between two contacting surfaces.
Students use a force sensor to measure the force applied to start an object in motion and drag it across a surface at a constant speed (constant speed is assured by monitoring the velocity of the object using a motion sensor). Assuming the object's speed is constant (net force is zero while the object is stationary and when it is moving), students can assume that the force applied to the object to start it in motion and drag it across the surface is equal and opposite to the frictional force experienced by the object. Using their graphs of applied force versus time, students identify the magnitude of the force corresponding to the static fs and kinetic fk frictional forces and record values for each.
In each trial, mass is added to the object, increasing the normal force and thus increasing both frictional forces. Students plot frictional (applied) force versus normal force for both static and kinetic force values. Using the slope of each best fit line, students determine experimental values for the coefficient of static friction and kinetic friction.
Combining these two proportionalities, students experimentally derive the equation that summarizes Newton’s Second Law.
The Ohaus Scout Pro Balance 2000g listed in the Materials and Equipment section is for classroom use, not individual lab stations.
This experiment may require software and an interface for data collection.