Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: kinematics language

From: Aaron Titus <titus@MAILAPS.ORG>

Ugh, I did it again! See how hard it is to be consistent? You are
right, it is improper to say that velocity decreases; it is proper to
say the y-velocity decreases (in this case because the +y axis is
defined to be upward).


<Devil's advocate>

How about *the magnitude of the y component of velocity* decreases? After all, a *component* is a vector isn't it? ;-)

</Devil's advocate>

The algebraic sign can indeed indicate a direction in a *pre-defined* coordinate system. It can also indicate a geometric relationship. Consider a kinematic example. If a and v_i are parallel, v_f will be greater than v_i (the particle speeds up). If a and v_i are antiparallel, v_f will be less than v_i (the particle slows down). This geometric ralationship is independent of any coordinate system.




Cheers,
Joe Heafner - Instructional Astronomy and Physics
Home Page http://users.vnet.net/heafnerj/index.html
I'll never be able to afford a Lexus, but I do have a Mac. Same thing.
DO NOT USE MY EMAIL ADDRESS ANYWHERE ON THE WEB!


Cheers,
Joe Heafner - Instructional Astronomy and Physics
Home Page http://users.vnet.net/heafnerj/index.html
I'll never be able to afford a Lexus, but I do have a Mac. Same thing.
DO NOT USE MY EMAIL ADDRESS ANYWHERE ON THE WEB!