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NSTA Web Seminar:
Force and Motion: Stop Faking It!
LIVE INTERACTIVE LEARNING @ YOUR DESKTOP
Thursday, January 15, 2009
Force and MotionForce and MotionCircular motion
Different frames of reference
Gravitational forces
Orbiting things
Circular motion
Different frames of reference
Gravitational forces
Orbiting things
Circular motion
In order to make an object go in a circle,
you must exert a force Toward the center of the circle
Along the circular path
Both toward the center of the circle and along the circular path
Both toward the center of the circle and away from the center of the circle
Use your clip art to respond
You have a string tied to an object. In which direction(s) can you exert a force on the
object using the string?
6
You have a string tied to an object. In which direction(s) can you exert a
force on the object using the string?
In order to make an object go in a circle,
you must exert a force Toward the center of the circle
Along the circular path
Both toward the center of the circle and along the circular path
Both toward the center of the circle and away from the center of the circle
Use your clip art to respond
Centripetal force is...A special force of unknown origin that pushes things toward the center of a circular path
A special force of unknown origin that pushes things away from the center of a circular path
A name given to forces that are already present and causing something to move in a circle
Use your clip art to respond
Let’s Pause for Two Questions from the
Audience
Different frames of reference
As a car rounds a sharp curve, you slide to one side because you’re not wearing your seatbelt.
What caused you to slide to the side of the car?
The car turned a corner but you continued to move in a straight line
A centrifugal force pushed you to the side of the car
The view is better next to the window
Use your clip art to respond
It depends on your frame of reference. Here’s the situation as
viewed from outside the car:
When viewed from inside the car, there is a centrifugal force that pushes you away from
the center of the circular path the car is taking.
Which of the following are true?
Centrifugal forces aren’t real. That’s why they are often called “fictitious forces.”
Centrifugal forces only show up when your frame of reference is rotating.
There is no such thing as a centrifugal force. You should never talk about them.
Centrifugal forces are as real as the force of gravity.
Use your clip art to respond
A “spin and barf” ride as seen from outside the ride:
A “spin and barf” ride as seen from inside the
ride:
Let’s Pause for Two Questions from the
Audience
Gravitational forces
24
Fgrav Gm1m2r2
25
Science Simulation from Gravity and Orbits
Science Object
Weight is:
The gravitational force the Earth exerts on an object
The gravitational force any object exerts on another object
The same as mass, but with different units
Use your clip art to respond
Is it possible to be weightless in outer space?
Yes
No
Depends on your frame of reference
Use your clip art to respond
It can seem to you that you are weightless when in orbit
Earth
You can create
your own gravity in
space
Let’s Pause for Two Questions from the
Audience
Orbiting things
Which drawing shows the forces acting on the Earth as it orbits the
sun?
Thank you!
Let’s Pause for Two Questions from the
Audience
Thanks to our presenter, Dr. Bill Robertson, and
to NSTA Press for sponsoring this program
http://www.elluminate.com
Elluminate logo
http://learningcenter.nsta.org
NLC screenshot
• NASA: Discover the Universe – From Galileo to Today
January 20,2009
• The NSTA Learning Center - Focus on Teachers
January, 21, 2009
• Picture-Perfect Science Lessons: Using Children’s Books to Guide Inquiry, Grades K-4
January 22, 2009
http://learningcenter.nsta.org
National Science Teachers AssociationDr. Francis Q. Eberle, Executive Director
Zipporah Miller, Associate Executive Director Conferences and Programs
Al Byers, Assistant Executive Director e-Learning
LIVE INTERACTIVE LEARNING @ YOUR DESKTOP
NSTA Web SeminarsPaul Tingler, Director
Jeff Layman, Technical Coordinator
