Identifying physics misconceptions at the circus: The case of circular motion

Abstract

Circular motion is embedded in many circus tricks, and is also one of the most challenging topics for both students and teachers. Previous studies have identified several misconceptions about circular motion, and especially about the forces that act upon a rotating object. A commonly used demonstration of circular motion laws by physics teachers is spinning a bucket full of water in the vertical plane further explaining why the water did not spill out when the bucket was upside down. One of the central misconceptions regarding circular motion is the existence of so-called centrifugal force: Students mistakenly believe that when an object spins in a circular path, there is real force acting on the object in the radial direction pulling it out of the path. Thus, one of the most frequently observed naïve explanations is that the gravity force mg is compensated by the centrifugal force on the top of the circular trajectory and thus, water does not spill down. In the present study we decided to change the context of the problem from a usual physics class demonstration to a relatively unusual informal environment of a circus show and investigate the spectators’ ideas regarding circular motion in this context. Thus, the goal of the present study is to examine the concepts of a heteroaged population regarding circular motion phenomenon provided in the context of a circus number as expressed in focus-group interviews following the number.