Hot Wheels, Conservation of Energy and Friction

A Demo for Grade 11/12 Physics Students

Created by Hayley Perkins

Learning Goals

This demo uses an everyday toy to demonstrate the complexity of real life physical systems, and to link together concepts from dynamics (2-D free body diagrams) and work and energy (mechanical energy, conservation, losses due to work by friction). It can be used as a review tool for Grade 11, a refresher for new Grade 12 students, or can be modified to review Physics 12 concepts.

What is it?

This demo involves creating multiple short Hot Wheels tracks, heavily stabilizing at least one, then comparing the final speeds of cars when put down the tracks. The final speeds give the class information about the initial height based on conservation of energy - but the students may be surprised to find that the calculated height does not match reality. This leads into an investigation of how to very roughly estimate the work done by the force of friction, and can facilitate a discussion of when and why we assume that physical systems are simpler than they are in real life.