S. PrasitpongR. ChitareeS. RakkapaoMahidol University2018-09-242018-09-242010-11-01Physics Education. Vol.45, No.6 (2010), 602-61013616552003191202-s2.0-78649502535https://repository.li.mahidol.ac.th/handle/20.500.14594/29942We present simple apparatus designed to help Thai high school students visualize the directions of frictional forces. Bristles of toothbrushes, paintbrushes and scrubbing brushes are used to demonstrate the frictional forces acting in a variety of situations. These demonstrations, when followed by discussion of free-body diagrams, were found to be effective in teaching frictional force directions. © 2010 IOP Publishing Ltd.Mahidol UniversityPhysics and AstronomySocial SciencesArticleSCOPUS10.1088/0031-9120/45/6/004