Activities in High-Speed Photography
The labs and activities listed below were written for a 2nd-year high-school physics class. They could also be used in introductory college physics courses. The labs all use high-speed images. In some cases, a series of high-speed photographs has been assembled into a video clip that can be played back to give an effect similar to a high-speed movie. (These are termed photo sequences below.) A video analysis program such as Tracker can then be used to extract data from the clip.
The level of mathematics required is indicated in parentheses.
The Bouncing Ball -- A Challenge -- A photo sequence of a ball bouncing across a table is shown without providing any information about the distance scale of the images. The problem is to determine the diameter of the ball indirectly, using the physics of projectile motion and the fact that the photos were taken on the surface of this planet. (Level: Pre-Calculus)
Average Force of Impact in a Tennis Ball Collision -- A photo sequence shows a tennis ball colliding with a wall. Measurements are made of the velocity of the ball before and after the collision and of the duration of the impact. The average force of impact can then be calculated. (Level: Algebra)
Deceleration of a High-Speed Projectile in Water -- A photo sequence shows the path of a BB projected downward into a tank of water at two-thirds the speed of sound. The displacement of the BB is measured as a function of time and compared to a theoretical equation that the student derives. (Level: Calculus)
Trapped! Analysis of a Real Collision -- The collision of a BB with an elastic strip is investigated through the use of multiple-image photographs. The force acting on the BB as a function of time can be found, yielding some interesting results. For more information, see the Inertia! project. (Level: Pre-Calculus)