Force and Motion: Stop Faking It!
The second of two Web Seminars on the topic of Force
and Motion was held on Thursday, January 25, 2007, from 6:30 p.m. to 8:00 p.m. Eastern
time. The presenter was Dr. Bill Robertson, author of the popular NSTA Press series
of books: Stop Faking It! The presentation focused on the topic of circular motion,
a topic discussed on Dr. Robertson's book: Force and
Motion: Stop Faking It!
Fifty-six (56) participants were present in addition to the presenter and the NSTA
staff. Participating educators represented the states of Arkansas, California, Florida,
Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, New
Hampshire, New York, North Caroline, Ohio, Oklahoma, Pennsylvania, Puerto Rico,
South Carolina, Tennessee, Texas, Washington, Wisconsin, and Wyoming. Some of the
participants had attended one of the two symposia on the same topic at the Area
Conferences in Omaha and Baltimore.
In this presentation educators had the opportunity to learn about circular motion.
Dr. Robertson explained that for an object to move on a circular motion at constant
speed, a force that acts toward the center of the circle must exist. That force
is called centripetal force. This force is the name given to all the forces that
are already present, that happen to cause the object to move in a circle. Dr. Robertson
also defined the term centrifugal force as the force that pushes the object away
from the center of the circle in which it is moving. To understand the idea of the
centrifugal force, Dr. Robertson described the concept of "frame of reference".
Only when you view things from a rotating frame of reference, a centrifugal force
appears. This force is very real to someone in that frame of reference. The centrifugal
force does not exist if you are not in a rotating frame of reference.
Dr. Robertson used diagrams from his book Force and Motion: Stop Faking It! Finally
Understanding Science So You Can Teach It to explain the concepts of centripetal
and centrifugal forces. He asked many questions to engage the audience and assess
their knowledge level. All participants received a copy of NSTA's
SciGuide on Force and Motion.
Here are some comments provided by the participants at the end of the Web Seminar:
- "This was a very informative session. I took physics in college but never really
'got it' and feel very uncomfortable teaching it."
- "I will be teaching science for the first time this fall, this was a useful
- "I start a unit on Force and Motion next week. I do not feel confident usually.
After tonight's discussion, I feel much more comfortable with circular motion."
- "Teaching physical science without a degree in it sometimes makes me inadequate
at doing it. Any education I receive only allows me to be better at educating my
Thanks to the participants and the presenter for the learning opportunity, the interactions,
and a job well done!
Web Seminar II Resources
recorded version of the Web Seminar.
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- PowerPoint Presentation (2.86 MB)
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Underwritten in part by NSTA Press