>> Welcome to Statics!
In any good course, it's important to sort of know where you are and
what you're going to be doing and where you're starting and where you're going and all that kind of stuff.
So I wanted to give you a sort of pre-overview of what this course studies.
In general, what we're going to be looking at is (well obviously) Statics, but
Statics is one of the branches of Mechanics.
Mechanics like Newtonian Mechanics, the study of the objects in the universe.
And that can be from the tiniest little thing to the biggest little thing.
We're studying how forces and moments and loads and stuff interact.
So this is sort of a, "Where are we today?"
You can sort of break Mechanics up in a couple different ways.
I like to think of it as -- excluding fluids -- as being broken up into Statics, Dynamics
and Solid Mechanics, or sometimes I'll just call it Solids.
Some people call it Strength of Materials.
Again, this is not, "Everybody does it this way."
Some people will say Statics & Dynamics, Solids, and Fluids, but in any event, what you've
got are sort of these basic pieces.
Dynamics is the part of Mechanics that studies acceleration and how things behave when they're
they are actually accelerating.
Strength of materials studies how things deform so that your beams in Strength of Materials
will actually bend.
In Statics, it's exclusion, the law of exclusion -- we're not studying fluids, we're not studying
stuff that accelerates, we're not studying stuff that deforms.
Stuff that neither accelerates nor deforms, that's what Statics is,
and that stuff can be a block of wood, a car, a universe -- whatever it is that's in equilibrium.
Our stuff will be broken down into three general groupings: Particles, which we will do before
the first exam; Rigid Bodies, which we will do before the second [exam] and stay with
until the third exam; and Systems of Things, which we will tackle only for the final exam.
So this is the stuff -- "stuff" is a highly technical term, but it's what we're going
to be actually studying.
We want to study the loads that act on it [our "stuff"].
And this might be a new word to you; you may be only familiar with the notion of a force.
We will also deal with moments.
Forces are things that tend to make "stuff" move linearly or accelerate linearly.
Moments are loads that tend to make "stuff" rotate.
So if you have a coffee cup and it tips over, there has been a moment applied to that coffee cup.
All of these things we will study the equilibrium of.
So how do the loads interact with the stuff for objects that are in equilibrium?
Which brings us to Newton's Laws!
Newton has a ... again, people will parcel these into different categories. This is how I think of it:
The first law is that an object in motion stays in motion unless it is acted upon by an outside load;
an object at rest stays at rest unless it's acted on by an outside load.
You will see -- probably some of you will have learned this with the word "force" here;
we're extending this now to include also moments. So that's our first law of Newton.
The second one is generally given to you as F equals m*a; sometimes you'll see that as
Newton's law of gravitation. This [F=m*a] is a special case of that [the law of gravitation].
What we're going to use is primarily weight equals mass times gravity.
That's basically what we're going to use, because we're not really considering other accelerations.
The only acceleration we'll have in this class is gravity.
And the third law, it says that if your stuff is in equilibrium, then
the sum of the loads that act upon that thing need to be actually equal to zero.
So that's what we're pretty much going to be doing for the rest of the semester:
summing the forces, summing the moments, setting them equal to zero.
That's where we're at.
We also use the same load we get to the very end of we're dealing with systems, and then
we're going to be talking about putting equal and opposite loads every time we consider
what one thing is doing to another thing.
So that's sort of your top-level overview of what this semester is actually studying.
We'll come back to these concepts over and over and over again over the semester so that
you can get your roadmap of where we are in the semester and what we're actually working toward.
Thanks!