Re: Kinematics of Throwing Balls

["S.Goelzer" <s.goelzer@ATTBI.COM>]

Hi
I find this to be the most persistent problem in this topics.

I found this demo helps _some_ students.

Tape a block of soft foam to the top of a dynamics cart (Pasco cart and
track). Block should be about the same volume as cart. Have student push the
cart using the foam. Student's finger should sink into foam when pushing.

Socratic method time:

How do you know when you are pushing?
(feel and SEE - maybe I should incorp a buzzer and switch too!)
When did the push end?
Did the push continue after you stopped touching the foam?
If the foam wad still being pushed after you stopped touching, what shape
would it have?
How is the motion of the cart different when you are pushing and when you
are not?

Push the cart to the student and have the student stop the cart by pushing
on the foam. More questions.

HTH
Scott




on 9/11/02 2:02 PM, Tina Fanetti at FanettT@QUEST.WITCC.CC.IA.US wrote:

> <<The force of the
> hand (which gave it the acceleration a) no longer acts on the ball.<<
>
> I bet this is the problem.  I think they think (and we haven't gotten=
> to force yet) that the force is still with the ball even after it le=
> ft the hand. =20
> I know one of my students has answered along these lines.
>
> Thanks
> tina
>
> Tina Fanetti
> Physics Instructor
> Western Iowa Technical Community College
> 4647 Stone Ave
> Sioux City IA 51102
> 712-274-8733 ext 1429

*****************************
S.Goelzer
Physics Teacher
Coe - Brown Northwood Academy
Northwood NH 03261
603-942-5531 ext43
sgoelzer@coebrownacademy.com
*****************************