General > General Technical Chat
Physics Question - ma = mg
RJSV:
'MAYHEM'?, 'BANANNAs'? I'm stealing all my jokes, from NOMINAL ANIMAL!
O.K. : BANANNAs it is:
(You) are pretty sure that 'Banannas per second' is a ridiculous term, but substituting 'loose' descriptors for actual precisely defined terms of PHYSICS is maybe OK. No, no,no:
'MOTION' is just a general umbrella term that could mean either, (or both) SPEED or ACCELERATION.
I think what got my attention, was a guy, back a ways, who posted that a parameter of ACCELERATION, well then that had to be a 'velocity' simply because he spotted the equation term: "PER SECOND". Must be a speed, right? ... No one will ever know!
Heck, even the term 'Specific Meaning' has no weight here.
SOOOO, For this reasons, I vote
NOMINAL ANIMAL for PRESIDENT
TimFox:
Try reading what I actually wrote. I did quote Newton’s original statements for historical purposes, but I carefully used the terms acceleration, momentum, and velocity when writing in my own voice. Modern versions of Newton’s theories are easier to understand and, where they are relevant (non-quantum and non-relativistic) are internally consistent and an accurate description of motion with its various attributes. For further discussion, please see any textbook on freshman physics.
RJSV:
Yes, Tim, I was a bit out of line by posting in generalities (like some people seem to 'smoosh' together a bunch of tech jargon, without accurate definitions.) But your latest posts, I like, just maybe a bit of time lag, as I comment addressed back a bit ( posts from couple weeks ago.)
But, still, not you but one recent post was directly confusing MOMENTUM (increasing) and saying that was 'WEIGHT' increasing (that being, again, momentum as mass X speed.) That's a pretty simplistic and not only wrong, but mis-leading (due to the fact that 'mass' is in the mix.
That (other) person's posts appear to me like an ignorant summary, saying 'No one will ever know' IE. the real use of equations and concrete/specific definitions.
Heck, I still see that (helpless) expressed, in the discussion of 'fluid ounces' and how that somehow complicates things, impossibly. Just: "no one will ever know". Yeah and 'Einstein'?!!! Gotcha there.
I think I will include 'Einstein'+ in everything I post.
Gives it an air of legitimacy.
Einstein ! Ha ha, gotcha again.
AND Thanks, I mean no insults here.
CatalinaWOW:
The disparagement of traditional systems leaves out poundals and a few other variants. These mass and force quantities are fine if kept straight, but the one real advantage of the metric system for anyone of average or above intelligence is that the metric community has done a better (not perfect) job of keeping them straight. Dimensional analysis is always useful. It was nearly mandatory in the traditional units world and still when referencing older texts. Even metric folk can miss out when using an older text that nonchalantly uses physical units expressed in cgs or slightly obscure units like wavenumber.
David Hess:
--- Quote from: JohnnyMalaria on June 25, 2021, 03:04:28 pm ---
--- Quote from: David Hess on June 23, 2021, 04:40:36 pm ---Go back to the beginning and figure out what is actually being measured. Scales measure *force* and not *mass*. Weight is force.
Units of pounds are force. The Imperial unit for mass is the slug, although in the industry it is more useful to talk about pounds force and pounds mass.
--- End quote ---
This is not true. It depends on which system of measurements you are using. e.g., the British Gravitational system does define pound as a force but the FPS system defines it as a mass. The UK legally defines a pound as 0.454 kilogram and, therefore, is defined as mass.
I was educated in the UK in the 70s and 80s. Pounds were always units of mass and pounds-force (lbf) specifically used to indicate force.
--- End quote ---
My point is that it is very easy to get into trouble with the unit pound because it can mean force or mass depending on the system, and literature will not always be explicit.
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