Introduction

Through my high school and university experience I have observed that many students find Newton's Third Law particularly hard to understand and believe.  Although it is Newton's hardest law to accept, it is by all means, not impossible to do so.  The obstacle of obtaining Newtonian clarity has motivated me to demonstrate that Newton's Third Law (Action-Reaction Law) is in fact true.  

The goal of my demonstration is to clarify the understanding students have of Newton's Third Law, in a 'seeing is believing' fashion.  This project was initially constructed for students of the 11th and 12th grade with minor knowledge of Newton's Laws of Motion, and potential and kinetic energies.  The audience is  encouraged to actively participate, and to ask questions anytime during the demonstration.

Newton's Action-Reaction Law is shown, and proved, through a series of collisions between carts.  Force sensors are mounted on the carts, which ultimately measure the forces, in newtons (N), felt by the carts during the physical interactions.  These forces are then displayed on a computer through the use of the LoggerPro software.  Much of the needed equipment was bought from Vernier (after extensive research I found that Vernier provides the most affordable prices, and high quality equipment).  'Head on' collisions are demonstrated with carts of equal and different masses.  Also, the forces felt by dragging the carts at constant velocity and at constant acceleration are shown.

The lesson plan that I created shows this demonstration for a class of roughly 75 minutes in length.  The demonstration has been successfully shown to two 12th grade classes from London Secondary High School, Richmond, B.C., Canada.