The didactic exploration of a toy
Jorge Valadares
UIED –Unidade de Investigação em Educação e Desenvolvimento-
- Faculdade de Ciências e Tecnologia – Universidade Nova de Lisboa
Abstract
This communication describes an investigative teaching strategy based on the exploration of a toy (a little plane). This is hung from the ceiling by means of a suction cup and has a switch that, in the “on” position, causes the rotation of a propeller, linked to a battery.
With the propeller turning and the plane away from its equilibrium position, when subjected to an appropriate short pulse, it soon starts to rotate horizontally.
The practically stationary motion reached by the aircraft can be considered circular and uniform because it achieves a situation in which the gravitational force, the pulling force caused by the propeller, the force of air resistance and the tension of the rope have a centripetal resultant.
With this little plane moving round it was possible to run a theoretical-experimental lesson with 1st year University students having two major objectives:
1th – A theoretical goal which is to review and deepen the knowledge about some concepts and laws of physics, such as: rigid body, particle, speed, velocity, acceleration, vector, components of a vector, tangential and radial acceleration, applied forces and link forces, components of a force, tension of a rope, gravitational force, pulling force, air drag, inertial force, equilibrium of forces, Newton’s laws of motion, conical pendulum, description of motions in inertial frames and accelerated frames.
2nd - A practical goal that is to get students to learn how to make the gathering and processing of experimental data and the statistical analysis of errors. They had the opportunity to learn and apply important concepts such as error, measurement uncertainty, normal or Gaussian distribution, arithmetic mean, moments about the mean, skewness and kurtosis, experimental standard deviation, expanded measurement uncertainty, confidence intervals, significant figure and the expression of measurement results.
In this communication it will be made also some brief remarks about the didactic approach and the classroom environment in order to provide a meaningful assimilation of knowledge and that it would please the students, as at the end was manifested by them in a written critical analysis that each of them produced.
Bibliography
Valadares, J. Didáctica da Física, Lisboa: Universidade Aberta, 2007
Cruz, A., Filipe, E.; Almeida, G.; Valadares, J.; Pellegrino, O. (2009). Medições e incertezas de medição: um contributo baseado nas convenções e resoluções internacionais. In Caderno Brasileiro de Ensino de Física, Vol. 26, N.1, Abril 2009, p. 125-135
Guide to the expression of uncertainty in measurement (GUM). BIPM, CEI, FICC, ISO, IUPAC, IUPAP, OIML, Ed. ISO, ISBN 92-67-10188-9, 1995