Re: Projectile Motion

[Rick Tarara <rtarara@SAINTMARYS.EDU>]

You have to spend some time working on the separation of the horizontal and
vertical motions.  I've been doing an in-class experiment where we fire a
projectile horizontally from the lecture desk but at different speeds, hence
different ranges.  Using the Pasco free-fall equipment and a photogate at
the launcher, one can time how long it takes to get to the ground.  This is
a good experiment to show that the vertical motion is independent of the
horizontal.  Also do the shoot the monkey demo.  I use my Animated
Chalkboard programs (free from the site below) to plot both the vertical and
horizontal motions of a cannon ball while watching the motion.  There is
also a version of the shoot the monkey.  I then give conceptual
quizzes--first asking everything about a ball thrown straight up
(velocities, accelerations, forces), then the same questions about the ball
in 2-D trajectory motion.  At this point we are ready to do 2-D problems!

Rick

*********************************************************
Richard W. Tarara
Professor of Physics
Saint Mary's College
Notre Dame, Indiana
rtarara@saintmarys.edu
********************************************************
Free Physics Educational Software (Win & Mac)
www.saintmarys.edu/~rtarara/software.html
NEW:  Mac versions of Lab Simulations
********************************************************


----- Original Message -----
From: "Tina Fanetti" <FanettT@WITCC.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Monday, September 23, 2002 11:40 AM
Subject: Projectile Motion


> If, I may, pull this list back to physics and the practical aspect of=
>  teaching physics...
>
> My college-algebra physics students had their first test over kinematics
incl=
> uding projectile motion.
>
> As I was grading the papers with increasing distress, every single st=
> udent got the same concept wrong.
>
> For some reason, they didn't get that in projectile motion, the initi=
> al velocity needs to be broken into its x and y components.  Now I di=
> d examples of this in class, it was on their homework and the day bef=
> ore the test I had them come to the board and workout  projectile pro=
> blems. =20
>
> Not a hint that they didn't get this distinction.  However I do give =
> them a formula sheet.  I had just given them the 1D equations and the=
> y were confused so I told them I would give it to them in components =
> form (yea I know..)
>
> So they  actually had the kinematic equations in x and y...
> Why don't they get it?
> How can I make them get it?
>
> Thanks Tina
>
> If this doesn't post I am going to scream...
>
> Tina Fanetti
> Physics Instructor
> Western Iowa Technical Community College
> 4647 Stone Ave
> Sioux City IA 51102
> 712-274-8733 ext 1429