Conservation of the speed of the CM of two particles under the action of frictional forces in one-dimensional motion (D = 1)

• Autor(a) principal: Souza, Carlos Eduardo Rodrigues
• Data de Publicação: 2019
• Outros Autores: Thomaz, Maria Teresa Climaco dos Santos, Souza, Dácio M.
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Caderno Brasileiro de Ensino de Física (Online)
• Texto Completo: https://periodicos.ufsc.br/index.php/fisica/article/view/2175-7941.2019v36n2p543

The force of friction is part of the daily life of the students and the understanding of their action on the bodies in the day-to-day brings the Science of their experience. We discuss the one-dimensional motion of two particles moving in opposite directions under the action of external kinetic friction forces. The law of the conservation of the total linear momentum involving these particles under the action of external dissipative forces is not discussed in general in the textbooks of Newtonian Mechanics used in upper and middle schools, in brazilian educational institutions.  We show that the conservation of the linear momentum of the set formed by the two particles under the action of two kinetic friction forces only occurs when their movement is unidimensional and in opposite direction. In this work, the conservation of the velocity of the CM is verified experimentally in a simple apparatus of low cost, which can be easily reproduced in the classroom as a strategy for encourage students to work with mathematical tools and experimental methods in order to discuss situations that include the frictional forces that belong to the day life of the student.