For those who want a new thread, here are a couple of starting points.
1) I had a couple of students come up after class and ask "So, when do
we get to the _good_stuff_?" After half a semester of projectile
motion with another half a semester of mechanics to come, I was at a
lost. Presumably they want to see nuclear power, quarks, and big
bangs; along with perhaps electronics or telescopes.
Is a whole semester of mechanics really the best way to introduce
physics? It's hard to look a student in the eye and tell them that
finding the landing point of a cannonball shooting from the top of a
wall at the top of a slope is vital to their education.
Do we scare (or just plane bore) most of our students by spending so
much time with mechanics, and kinematics in particular?
2) I argue that all of kinematics is math, not science. Any competent
mathematician could discover the first 4 chapters of any general
physics text without any reference to the real world. Or in other
words, none of it is experimentally falsifiable.
Since we _define_ a = dv/dt = d2x/dt2, all of the other kinematic
equations are true by definition!
In fact, you can consider Newton's first two laws as definitions,
making the third law the first real physics incountered in general
physics, typically 6 weeks into the class. And then it is relegated to
second class status, while the students grind through dozens of second
law problems.
3) As a partial solution, why not jump in the first day with an
airtrack and a couple of ultrasonic motion detectors and "discover"
conservation of momentum. After a bit of practice, try an airtable and
introduce vectors.
After a week or two of momentum, apply a constant force to an aircart
and "discover" the work-energy theorem. Then move straight into
conservation of energy.
Within a month, the students know two of the cornerstones of physics.
At some point, you will probably want to work back to kinematics. But
you also have the ability to talk about thermodynamic energy, energy in
moving fluids (i.e. Bernouli effect), nuclear energy, E=mc^2 energy and
the rest of the _good_stuff_.
Does anyone know of a good text that uses this approach? Or should I
get busy writing one?
--- Tim
----------------------
Timothy J. Folkerts email: tim.folkerts@valpo.edu
Department of Physics phone: 219-465-2134
Valparaiso University
Valparaiso, IN 46383