So I'm watching this show about physics and the cosmos and stuff last night and the topic of the "conservation of angular momentum" comes up. I find a few articles pretty quick and realize I pretty much understand most of it already - except for that big fat title of course. 😉
Anyway, I dig out one of my old/ancient physics text books to see what it has to see what it has to say. Wow! Talk about some out of date terminology!!!!
Granted this book is copyright 1954 from when Dad was in college. But gees!!
Anyone ever heard of a "poundal" before?
How about a "slug" - and no, I'm not talking about shell-less snails, shotgun ammo, or fake nickels. I had to look at the mathematical definitions to understand exactly what they meant in the way they tried to explain it. "They" = "this author" of course.
If you have heard of these things before in regards to physics, I don't recommend admitting it lest you really show your age!! 😀
Man is this book dated - beside being pretty thin on substance.
Ch. 8 - Kinematics of Rotation .... all 6 pages.
Ch. 9 - Dynamics of Rotation .... 15 pages.
I don't mean to be putting it down or stuff and granted this is a 1st year college physics text, but I'd swear my high school physics book had to be at least twice this size.
At least I learned a few things today anyway. That should hold me for the rest of the week. 😀
E.
Slugs, Yes, Poundals, No
But then I had to repeat a Physics course.
Curiously the summer grad student instructor was a farm boy and my dad needed to hire some help in his farm equipment shop, easy "B".
Besides farm equipment we did some interesting work. My dad wanted to lay out a survey line for cutting. Well we borrowed, sort of, a laser from the Physics department and set it up at night. That laser penetrated through a lot of leaves. The laser was three feet long and on the back of a pickup truck, but once aligned it went quite a distance. Don't know if it made the job any faster but it was fun.
Paul in PA
Must be older than dirt because I do remember both of those terms. Don't ask me to provide the exact definition, though. We used to make up new velocity terms to break up the dullness of our studies. Rates such as furlongs per fortnight.
Anyone remember the formula for horsepower being 2 x pi x R x F x N all divided by 33000. The key being that you had to have the correct units on the R (effective radius of the lever arm in feet), F (force in pounds) and N (revolutions per minute) to make the 33000 work as the magic number.
Yes, indeed. Works like this:
(2? feet)/(1 Revolution) × (F Pounds)/1 × (N Revolutions)/Minute × (1 minute)/(60 seconds) × (1 horsepower)/(550 foot-pounds)
All the units, except Horsepower, divide out.
=2?FN/33000 Horsepower
And if the units are right, then the answer is probably right, too.