Vernier Software and Technology
Vernier Software & Technology

2D Vectors: Pool Ball Displacement, Velocity, and Speed


A careful analysis of two-dimensional motion is more complex than it is for motion in one dimension – especially when calculating velocities and speeds. In this activity you are going to analyze a movie that shows the 2D motion of a pool ball rolling on a level pool table. The ball starts with its center at point A, moves “up” and to the left to point B, bounces off the edge of the table and rolls “down” and to the left so that its center reaches point C.


In this activity, you will

  • Scale a movie.
  • Use displacement vectors to find average speed and average velocity.
  • Show that the magnitude of the average velocity, \left| {\left\langle {{{\vec v}_{{\text{A}} \to {\text{C}}}}} \right\rangle } \right|, of object moving in 2D is not always the same as its average speed, \left\langle {{S_{{\text{A}} \to {\text{C}}}}} \right\rangle .

Software for Experiment

This experiment uses Logger Pro software for video analysis. The video for analysis is included with the lab book.

Experiment 9 from Physics with Video Analysis Lab Book

<em>Physics with Video Analysis</em> book cover

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

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