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.