A Broom to Sweep some Pre-concepts and Introduce the Torque Concept

Abstract

If a body is cut vertically passing through its center of gravity, it seems surprisingly easy to suppose that its parts have the same weight. It’s necessary “to sacrifice” a broom to show that the common sense is not right, to see that the difference of weight is more than the error of cutting. The experiment surprises the students and leads them to think on alternative explanations, giving occasion to introduce the concept of torque. We also give another related example that attempt against the common sense.