An Interesting Look at Free Fall

Photo by AleGranholm

A group of Yale physics students used a video camera to analyze the motion of a ball as it fell. The ball was positioned in front of a large measuring scale so its height above the ground could easily be determined. The students reviewed the video of the falling ball frame-by-frame. They used the scale in the background and the video's timecode to study the motion. The following graph shows the expected behavior of a ball in free-fall (neglecting air drag):

This graph show's the actual behavior of the falling ball:

Notice that the second graph is noticeably different from the first one--apparently, the ball did not fall as an object in free-fall! 

Reaction Times

A group of high school students investigated how human reaction time is affected by drinking various soft drinks as part of their year-end physics project. They tested water, Gatorade, and Diet Mountain Dew. Their results are summarized in their report.

They also produced a nice video that documents their procedure.

High Speed Photography

As their year-end project, a group of physics students experimented with high speed photography. They used a PASCO photogate to connected to a strobe light. The strobe was the only source of light in the room, so the students were able to automatically capture the photo at just the right time. The photos below show a table tennis ball and a bottle cap splashing down into a beaker of water.

The Ballista

As their year-end physics project, a group of students designed, built, and tested a ballista. They also recorded various attributes of the arrow's trajectory. For complete details, watch the summary video:

Medieval Trebuchet

The completed trebuchet is prepared for launch.

A sample of the group's calculations.

As part of a year-end project, a group of high school physics students created a working trebuchet. The trebuchet was a cross-curricular project, counting for both physics and history classes. For physics, the students working out the theoretical range, trajectory, and speed, and compared to the actual results. Watch the group's video for an overview.

This video show's the trebuchet in action at the first inaugural renaissance festival: