This paper presented by the author at the Third International Seminar - Misconceptions and Educational Strategies in Science and Mathematics, held at Cornell University, has as its main theme the misconceptions resulting from the spontaneous thinking of students and teachers of high school physics about the relativity of mechanical magnitudes. It is based on a research work carried out by Villani and Pacca with a questionnaire produced by these two professors and Brazilian researchers that applied them to a sample of Brazilian students graduated in Physics. The author of this communication used this questionnaire with only one more question and applied it to a sample of 53 teachers of Physics with very varied experiences in the teaching of this subject.. The conclusions drawn from the research with teachers were identical to those that were withdrawn by the Brazilian researchers with the students graduated in Physics.