Is a passenger in an accelerating car "thrown
back" by some force, or does it just seem that way? Brian and Nikki made a movie, throw.mp4 (589KB), of an accelerating toy truck and its passenger to find out. They also made another movie, throw-d.mp4 (14MB), explaining how they did it.
Brian and Brian made a movie, fall.mp4 (333KB), of a falling meterstick that you can use to measure the acceleration of gravity. Just mark the point on the computer monitor (with a bit of tape, perhaps) where the end of the meterstick is in the first frame, then read off the distance it falls in each following frame. Plot these numbers versus time (each frame is 1/30 s) and fit the graph to a parabola. They also made another movie, fall-d.mp4 (9MB), describing how they made the data movie.