NSTA Web Seminar:

Force and Motion: Stop Faking It!

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Thursday, January 15, 2009

Force and MotionCircular 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 pathBoth 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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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 pathBoth 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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Fgrav Gm1m2r2

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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