We describe a simple experiment about sliding friction of an object moving with non-constant speed along an inclined plane. This experiment can be used to study the entire dynamical process of force and motion in various ways, depending on the mathematical level of the students. We discuss how video measurement and analysis, and mathematical modelling with adequate computer tools let upper secondary students focus on physics concepts, move back and forth between theory and practice, and make connections between all involved quantities, without being distracted by cumbersome measurements and calculations. We also present some advanced models for friction phenomena that become within reach of students via computational modelling.