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Re: impulse/momentum



The conveyor belt (taking on sand) is also a good pre-problem for your
query.
The big difference is that if the water is to bounce off with an
undiminished speed, the proper model is an elastic collision, whereas the
proper model for the conveyor belt situation is a totally inelastic
collision.

(We didn't forget you, we just get wrapped up in our own musings!)

Bob Sciamanda
Physics, Edinboro Univ of PA (Em)
http://www.velocity.net/~trebor
trebor@velocity.net
----- Original Message -----
From: "Justin Parke" <FIZIX29@AOL.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Saturday, December 13, 2003 5:31 PM
Subject: Re: impulse/momentum


The first time I sent this it was difficult to distinguish my comment from
the original message
msylvest@XNET.IT writes:

PS looking back over the thread, I see Justin Parke asks "Any suggestions
on a problem that requires a student to understand/apply impulse and
momentum considerations to "continuous" systems like ropes, water, etc?"

I like to introduce this kind of calculation with the "cement factory
problem": A skip drops sand onto a conveyor belt, at a steady rate. The
conveyor belt maintains a steady speed. They find the force needed to keep
it going. The further discussion of where the energy dissipation occurs,
and the role of friction in the process is also interesting.




My Comment:
Thank you! I must admit to feeling a bit forgotten by the parties in the
discussion.