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.
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.
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