The parabolic trajectory of a kicked ruby ball!



Teachable Topics:

  • Projectile Motion
  • Newton's Laws


During the moment when the ball is kicked, it has a vertical and horizontal component to it's motion. Once the ball is in the air, the only force being applied to the ball is gravity, and it is now in what is known as free-fall. Since there is an acceleration negative to the balls motion, the ball's upwards velocity eventually slows to a stop and begins to fall back down to the ground (still accelerating due to gravity). The force of gravity, however, has no effect on the horizontal component of the balls motion. This means the ball keeps going at a constant horizontal velocity (however this is not possible in the real world, as the ball is subject to air resistance and friction). All this comes together to make the ball travel in a parabolic arc as seen in the video. 


  1. Take a ball of any kind.
  2. Take aim.
  3. Kick!

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