Average Speed Puzzle – Large Version


The apparatus
The apparatus

Even though the two balls fall through the same vertical distance and have the same initial and final speeds, one ball reaches the end of its track first because it has a higher average speed.



Principles Illustrated

1D Motion and graphs. Using the SONAR for position and velocity matching is one of the most effective ways for students to learn what position, velocity, and acceleration mean and how to interpret graphs.

NCEA & Science Curriculum

SCI 1.1, PHYS 2.4


This demo works well with the multiple choice cards or clickers (personal response system). Ask students or groups of students to predict which ball will arrive first and hold up the corresponding card or enter their answers with the clickers. This gives an immediate sense of how many students understand the principles. Then do the demo. Typically most students in a class will predict that the balls arrive at the same time.

Transparency for use with this demonstration: Transparency.pdf


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

Average Speed Puzzle – Small Version.

Teaching Resources

Would you like to contribute lesson suggestions? Contact us.


PIRA 1D15.20


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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