The 'spinning disk touches stationary disk' problem revisited: an experimental approach

Gomes, Mário S.M.N.F. ; Martín-Ramos, Pablo (Universidad de Zaragoza) ; Pereira da Silva, Pedro S ; Ramos Silva, Manuela

Resumen: A popular Newtonian mechanics problem, featured in textbooks, physics olympiads and forums alike, concerns two disks with different radii and moment of inertia that rotate differently and that touch each other. Most students struggle to calculate the final angular velocity of the disks, erroneously attempting to use different conservation laws. In this paper we propose a simple experiment that should help physics teachers explain this challenging exercise in an engaging way for the students. By using a smartphone/tablet and video analysis tools, the angular velocity of both disks can easily be tracked as a function of time, clearly showing the three stages of the interaction (before touching, only one disk rotating; touching with slippage; and touching without slippage). Processing and plotting of the data in a spreadsheet immediately shows which quantities are conserved and which are not. Several extensions to the core experiment are also suggested.

Idioma: Inglés

DOI: 10.1088/1361-6404/aab98b

Año: 2018

Publicado en: EUROPEAN JOURNAL OF PHYSICS 39, 4 (2018), 045709 [9 pp.]
ISSN: 0143-0807

Factor impacto JCR: 0.861 (2018)

Categ. JCR: PHYSICS, MULTIDISCIPLINARY rank: 64 / 81 = 0.79 (2018) - Q4 - T3
Categ. JCR: EDUCATION, SCIENTIFIC DISCIPLINES rank: 34 / 41 = 0.829 (2018) - Q4 - T3

Factor impacto SCIMAGO: 0.441 - Physics and Astronomy (miscellaneous) (Q2)

Tipo y forma: Article (PostPrint)

Área (Departamento): Area Ingeniería Agroforestal (Dpto. CC.Agrar.y Medio Natural)