Re: Force sensors (2)

[jmclean@chem.ucsd.edu (James Mclean)]

Rauber, Joel              Phys says:
> b) Do you really think its stretching the point.  When you use a spring 
> scale to measure a force the procedure is as follows:
>
> 1) You put the spring in equilibrium.  This is the step where you measure 
> the acceleration.  You must measure the acceleration to be zero in order to 
> know that the spring is in equilibrium.

Actually, you must measure the spring elongation to be constant over time.
This does mean that the acceleration is zero, but the converse doesn't
work: acceleration = 0 is not sufficient to conclude that equilibrium has
been reached.  The velocity, jerk, ... must also be zero.

Not to mention that I think everyone else in this discussion is refering to
measuring the acceleration which is related to the force by N1.  It's not
clear why discussion of internal accelerations is helpful here.

-- 
--James McLean
jmclean@chem.ucsd.edu
post doc
UC San Diego, Chemistry