Re: kinematics language -- Re: kinematics, traditional or not

[paul o johnson <pojhome@SWBELL.NET>]

----- Original Message -----
From: "Aaron Titus" <titus@MAILAPS.ORG>
To: <PHYS-L@lists.nau.edu>
Sent: Wednesday, August 28, 2002 8:49 AM
Subject: kinematics language -- Re: kinematics, traditional or not

> The words "increasing" and "decreasing" can be confusing if one isn't
> careful to distinguish between the magnitude of a quantity and the
> quantity.  I use this example in my class: If your checking account
> is in overdraft protection with a balance of -$400 and you deposit
> $300, has your balance increased or decreased? <increased>  Has "how
> much you owe the bank" increased or decreased? <decreased>

----- My comment: -----

It seems to me that one needn't be too careful  to distinguish between the
magnitude of a quantity and the quantity. By "quantity" I assume that you
mean vector, a "quantity" that has both magnitude and direction. If I say
that the vector is decreasing, what else can I mean other than that the
magnitude of the vector is decreasing? Can the direction of the vector
decrease or increase? I don't see any confusion here.

poj