A CameraScope Physics Example
Measuring the velocity of a falling object using digital video is a valuable activity that helps students to understand this highly abstract concept in a very concrete way. Using an inexpensive web-cam, students record the dropping a ball from 2 meters against the backdrop of a meter stick for subsequent real-world calibration.
The height of the ball is measured at each frame of the movie (.033 second increments). The resulting data file is brought into Excel and graphed. with trend-line analysis showing a near-perfect (r2 > .99) fit to the theoretically expected velocity curve (a second order polynomial). The force of gravity can then be calculated easily to a high degree of accuracy when compared to the theoretical 9.8 meters/second2.