Re: [Phys-L] Sequence

[Philip Keller <pkeller@holmdelschools.org>]

If I were going to try this approach, I would in fact limit motion to
positive velocities.  I see the appeal of forces before kinematics.  But I
want to be able to refer to constant velocity vs constant acceleration as I
teach about forces.  So I would leave this nit unpicked until I came back
to kinematics later.


On Thu, Mar 20, 2014 at 9:31 AM, Rauber, Joel <Joel.Rauber@sdstate.edu>wrote:

> One nit to pick.
>
> Phillip K wrote in part:
>
>
> But what if the ONLY things you wanted to get across were:
>
> PART I -- here is one kind of motion we care about.
> 1.  When an object moves at a constant speed in a straight line, its
> position graph is a line.
> 2.  In that case, the slope of that line stays constant.  That slope is
> the speed.
> 3.  Since the speed is not changing, the "velocity" graph is a horizontal
> line.
>
> [:]
> [:]
> The slope is the velocity not the speed.  If the object were moving at a
> constant speed in the opposite direction the slope would be negative, the
> sign indicating the direction of the velocity vector in a 1D situation
> (which I'm assuming is what is happening here).  Unless you only allow
> objects to move in the positive direction of how you oriented your
> coordinate axis.
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