View from rotating camera


Image copyright: Donald F. Collins and Warren Wilson College

The camera is mounted on a superstructure that rotates with the table.  When the camera looks down onto the table, the table looks stationary.  However, you can see the students' feet walking on the right edge of the table as the students are rotating the table.  You can also see the glare of the ceiling lights reflected on the table. 

As the frictionless puck is shoved across the level table, it appears to be deflected to its right.  This deflection is called the Coriolis effect.  Whenever a body moves across another body that is rotating, it is deflected by the Coriolis effect.  When winds on the rotating earth flow toward a low pressure area (such as the center of a hurricane or cyclone) the winds are deflected toward the right in the northern hemisphere and cause the rotation of the hurricane.

However, the puck is actually travelling in a straight line relative to the stationary laboratory (ceiling, floor, walls) as shown below:

View from fixed camera


Image copyright: Donald F. Collins and Warren Wilson College

The experiment was repeated by photographing from a camera mounted on the fixed ceiling.  The table was rotated underneath the camera, and the fixed camera sees the table rotate.  Because of the lack of friction, the table rotates underneath the frictionless puck and the puck glides straight across relative to the fixed camera as shown by the red trails.  The straight line, constant velocity motion of the puck is governed by Newton's Law of Inertia: a mass in motion in the absense of forces (no friction) continues in a state of constant motion.  Relative to the center line in the table, the straight-line moving puck appears to veer to the right of the center line, even though the puck is travelling straight.

This experiment was performed by the Physical Science Class in May, 2004* at Warren Wilson College.  Special thanks is given to Physics Department assistant Omar Barnaby who digitized the video clip.  Professor Donald Collins assembled the animation.

*Members of the class:
Heather Child, Kristen Cole, Jill Collins, amanda Grover, George Keel, Amanda McGaha, Christopher Metzloff, Jesse Paluch, Matthew Sanders, Brian Shorb, Nathan Smith, James Tyson

Tropical Storm Ivan left a trace of its barometric pressure.  The barographs for both Frances and Ivan can be seen in a previous Physics Photo of the Week page on the barograph.

Physics Photo of the Week is published weekly during the academic year on Fridays by the Warren Wilson College Physics Department.  These photos feature an interesting phenomena in the world around us.  Students, faculty, and others are invited to submit digital (or film) photographs for publication and explanation.  Atmospheric phenomena are especially welcome.  Please send any photos to dcollins@warren-wilson.edu.

Click here to see all Physics Photo of the Week for 2004.