NSTA Web Seminar: Force and Motion: Stop Faking It! LIVE INTERACTIVE YOUR DESKTOP Thursday, January 15, 2009

Force and Motion Circular 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?

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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

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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

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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,

National Science Teachers Association Dr. Francis Q. Eberle, Executive Director Zipporah Miller, Associate Executive Director Conferences and Programs Al Byers, Assistant Executive Director e-Learning LIVE INTERACTIVE YOUR DESKTOP NSTA Web Seminars Paul Tingler, Director Jeff Layman, Technical Coordinator