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Re: Projectile Motion



I totally agree - use whatever apparatus you can scrounge up to produce
consistent projectile motion and have the students try it for a variety
of angles. They will come up with questions on their own that will
suddenly turn the lights on for them. Even your best students have to
get their "hands dirty" on this before they really understand it.

Best of luck
Bob at PC

Rick Tarara wrote:

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