Resumen: This paper describes an experiment with two touching rotating disks, whose movement is followed by video analysis. Within the disks’ movements, there are intervals with sliding and intervals without sliding, that is, intervals with frictional forces between the touching surfaces and intervals without it. This system configuration allows for measurement of the changeable magnitudes and directions of frictional forces (much more difficult to set up with translational motion). This activity may be used to combat students misconceptions of “frictional force always opposes the motion” and “between the same two bodies, one gets the same frictional force,” commonly found in the classroom, or just to reinforce the rotational dynamics relationships. Idioma: Inglés DOI: 10.1119/1.5145473 Año: 2020 Publicado en: PHYSICS TEACHER 58, 4 (2020), 260-262 ISSN: 0031-921X Factor impacto JCR: 0.701 (2020) Categ. JCR: PHYSICS, MULTIDISCIPLINARY rank: 75 / 85 = 0.882 (2020) - Q4 - T3 Categ. JCR: EDUCATION, SCIENTIFIC DISCIPLINES rank: 41 / 44 = 0.932 (2020) - Q4 - T3 Factor impacto SCIMAGO: 0.41 - Physics and Astronomy (miscellaneous) (Q2) - Education (Q2)