Year 12 Mechanics ball race Experiment:


Purpose:

  • 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.



Equipment:

  • Ball tracks (OHP version or wooden version)

Method:

  • Place two ball bearings at the same start position and the same initial velocity and ask students to guess which ball will get to the end first.
DoubleBallRamp.jpg
Two ramps, one behind the other.
TracksSmall.jpg Tracks_on_Overhead_Small.jpg c2-11.gif
A+05+10.gif

Pitfalls / causes of error / Hints:

  • 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.

Resources

  • PDF OHP sheet (New Zealand Physics Teachers' Resource Bank hosted by Victoria University of Wellington)
  • racing_balls.jpg
    An excellent animation for those who do not have the gear
  • ball_race2.jpg
    Another animation, this one with a more severe difference

Model data:

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References / other comments: