Friction is a phenomenon that we have all experienced even if we didn’t understand it. You might recognize it as the sound of chalk on board, music from an instrument, noise from doors squeaking. The fact that a violin produces music is a result of friction as an oiled bow will not play.
Students in Peter LaMoreaux’s physics class are studying the intricacies of friction by experimenting with different objects around the classroom in the Slip-Stick Lab. Some students are sliding watering cans filled with water across a lab table, others are dragging calculators, one student group slid blue painter’s tape.
Students collect data with a variety of handheld spring scales, which are attached to the object being slid. An internal spring measures force associated with the sticking and slipping that occurs when the object is dragged over the surface.. With the measured values, students then calculate coefficients of friction between different interacting surfaces. They are also working to determine trends for a variety of experimental conditions.
“The idea of the lab is to give students experience with the force of friction and the idea of the coefficient of friction between surfaces,” explained teacher Peter LaMoreaux.
“The trend is the more water in the watering can, the harder it is to pull and the more friction,” explained tenth grader Max Matthews.
Radhika Kumar, an eleventh grader weighing weights on a clipboard said, “When the weight goes up so does the mu (Greek letter) or the coefficient of friction. It’s a ratio that measures how much frictional force resists the motion of two surfaces in contact.”
Without friction students learned that everything would slide to the lowest point: no writing, no riding a bike, no driving in cars. It’s a powerful lesson for a physics lab.
