One other detail: Am I the only one bothered by expressions such as
"KE is conserved" in elastic processes? To me, that sends students
the wrong message. I'd rather say "mechanical energy is conserved
throughout the process, KE being stored partially or entirely as PE
during the collision and is then converted back to KE after the
particles separate, *because* the interaction forces are
conservative, namely they're elastic, gravitational, or
electrostatic". Otherwise students have a hard time with some of the
usual textbook problems such as maximum compression of a spring
bumper during collision of two air carts, gravitational slingshot of
a satellite around a planet (what is the "magic" that happens while
the satellite is near the planet?), interactions of point charges
(they'd have to be infinitely far away before you can say E_mech is
only KE), etc.
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Carl E Mungan, Assoc Prof of Physics 410-293-6680 (O) -3729 (F)
Naval Academy Stop 9c, 572C Holloway Rd, Annapolis MD 21402-5002 mailto:mungan@usna.eduhttp://usna.edu/Users/physics/mungan/