Newton’s First Law on an Air Track


A typical air track
A typical air track

A cart moves with nearly constant velocity and the very low friction air track.

Principles Illustrated

Persistence of motion (constant velocity) when no external forces act on system.

NCEA & Science Curriculum

SCI 1.1, PHYS 2.4


Set cart in motion and observe. Note that the cart must be balanced. If an extra mass is placed at one end of the cart then the cart will sit on the track at an angle. This can cause a quite noticeable net force on the cart, accelerating it with the heavy end forward as the angled cart forces air backward. In this picture a fan has been added to the right end of the cart and a balancing mass has been added to the back end of the cart. The fan was not running in this demo but was used for Newton’s Second Law on an Airtrack.


Individual teachers are responsible for safety in their own classes. Even familiar demonstrations should be practised and safety-checked by individual teachers before they are used in a classroom.

Related Resources

See Newton II demo on air track.

Teaching Resources

Would you like to contribute lesson suggestions? Contact us.


PIRA 1F30.10


This teaching resource was developed with support from

The MacDiarmid Institute
Faculty of Science, Victoria University of Wellington
School of Chemical and Physical Sciences, Victoria University of Wellington


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