Kinematic equations (Was: Crib Sheets)

[Jon Bell <jtbell@cs1.presby.edu>]

 Rick Tarara <rtarara@saintmarys.edu> wrote:
> [...]  I HATE books that produce a separate set of kinematics 
> equations for projectile motion (with y's for the vertical motion and 
> substituting 'g' for the acceleration).  This just reinforces student's 
> belief that physics is just a bunch of equations to be 
> memorized--specific equations for each problem.  I force students to work 
> such problems with ONLY the 4 standard kinematics equations--WHICH I 
> constantly stress are all derived FROM the DEFINITION of acceleration!

I've something like this, but I used just *two* kinematic equations:

	x = x0 + v0*t + 0.5*a*t^2
	v = v0 + a*t

One constructs a standardized diagram that looks something like this:

         start        (a = ?) --->              finish
           X---------------------------------------X
        (t0 = 0)                                t = ?
         x0 = ?                                 x = ?
         v0 = ?                                 v = ?

Then one fills in whatever initial quantities are given, and solves the x
and t equations as necessary to get the unknowns.  This means re-deriving
the other two "basic kinematic equations" every time one needs them.  Of 
course, most students prefer to memorize the equations instead.

-- 
Jon Bell <jtbell@presby.edu>                        Presbyterian College
Dept. of Physics and Computer Science        Clinton, South Carolina USA