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Re: Setting up problems

Perhaps I can get the topic back.

I just came from my class and had a discussion with the class after a quiz on work and energy.

Students commonly state, "I know the concepts. I have them memorized."

They also are demanding the kind of "plug and chug" problems they have grown accustomed to doing.

One example problem from the quiz:
_____________________

A roller coaster starts from rest at the top of an 18-m hill. The car travels to the bottom of the
hill and continues up the next hill that is 10.0-m high. (a diagram of the situation is given with
the problem) How fast is the car moving at the top of the 10.0-m hill, if friction is ignored?
______________________

Students can tell me, if I give them the mass, what the potential energy is at each location.
The fact that the mass isn't given really makes them crazy. They do not even know how to start the
problem without it. During the quiz I told them that the mass isn't needed and that they should
proceed by considering what exactly is going on and write down the appropriate equations.

In class I did a few examples for conservation of energy after a few examples on potential energy
and kinetic energy separately. In talking about conservation of energy, I used the example of the
bob sled sliding down a hill. At numerous points on the hill, I wrote down the kinetic and
potential energies of the car and showed that the total is constant.

Students describe their difficulty as "understanding the definitions," "being able to calculate
quantities," but not being "able to apply the concepts" to solving a problem.



I don't understand how this fits into the preceding dialogue. It seems to
take the phrase "rlated equations" out of the context in which it had been
used.
Regards,
Jack


On Wed, 8 Oct 2003, Bernard Cleyet wrote:

"I think, Bob, what people were responding to is the part about
'have them look at the related equations'".



OK here's related equations:

The generalized solution for numerical modeling of two dimensional
orbits is:

Q(i) = AX(i)(x^2 + y^2)^B where to model the earth: