Fluids, Heat, Electricity, and Magnetism
If you are new to physics, go back to mechanics and learn forces and motion first. This page is about forces and motion too, but the other is more fundamental. About fundamentals: they are fun, and they are mental (da). Most of this is in your textbook; the treatment here is shorter.
Some topics below have simple sketches that do not take up much computer memory. The topics that you probably need to know for a physics course about have * in front of the links.
For steady flows, there is an Ohm's law type of relationship in the flow of
viscous fluid, flow of heat energy, or flow of electric charge. To find out
more about this, which your text probably doesn't discuss, go
with the flow. Another thing that links these topics together is that when
the rate of change of u is proportional to
uf - u, where u is some quantity that will change gradually to uf
, then
u = uf + (uo - uf )e-t/t where 1/t is the constant of proportionality. There are many things that vary by this equation, including some found
in the topics of fluids, heat, electricity and magnetism. Take something out of
the refrigerator, for example, and u is temperature T. In electricity, the
voltage on a capacitor will vary that way too (under the right conditions).
For all the rest we treat fluids, heat, etc. separately. The above stuff is glopped together with a one equation fits all approach.
You want to learn something? Then teach it to others, and you will learn more than they do.
Winemakers: You must know (pun intended) about the siphon (but this is more than you wanted to know, so do not click on it).
Fluids: Check out *pressure and buoyancy, DP = rgDh is the pressure change as you go deeper in a fluid, and this is the cause of the buoyant force. Or *pressure vs velocity in a non-viscous (but possibly vicious), smooth flow. (Principal players here include Archimedes and Bernoulli.) Find why the curve ball curves. *Pressure, density and temperature of an ideal gas (which doesn't exist, but the equations are only a little off for a low density gas, which nature abhors). PV = nRT and all that. In *kinetic theory of gases, we find how pressure is related to kinetic energy of molecules, PV = 1/3 Nmv2 so PV = 2/3 of the kinetic energy, and this leads to the theory of heat capacities, not only for gases, but for some solids and liquids.
Get energy from the wind. (Power in the wind is 1/2 Arv3 .) If you want to know about the various molecular speeds in a gas, look at the Boltzmann factor and the Maxwell-Boltzmann speed distribution.
Heat: Put some dishes into hot water or ice cubes into a drink and find the final temperature (*specific heat capacity and *heat of fusion and vaporization). DQ = cmDT and Q = Lf m
Heat energy can do useful work. To be more specific, heat has the capacity
to power an engine (lite, nonfat *thermodynamics). It
turns out that you cannot possibly convert all or even a high percentage of heat
energy into useful work. The maximum theoretical efficiency is
1 - Tc / Th , where those T's are the colder and hotter
temps involved. Here
is a problem that looks like (but isn't) a violation of the Conservation of
Energy principle: Open it.
Electricity: The dreaded static cling and all that (*descriptive statics). *Coulomb's law = Gauss's law, sort of. In terms of electric field, Coulomb's law is E = kq/r2 , and Gauss's law is E times area = 4p kq. You will get a charge out of *capacitors. They store charge, and charge q is proportional to voltage, so q = CV defines capacitance C. Find out about that yin-yang pair, the mho and the Ohm: *Ohm's law, V=IR, concerning flow of charge (current I thru resistance R). Find what is wrong with Ohm's law. (Electric) power to the people! *Circuits (series, parallel combinations). Or go beyond series and parallel into circuit nirvana or hell, depending on your point of view.
*Know the units and you will automatically know a lot. For example if you know that a volt is a joule/coulomb, then you can figure out the kinetic energy of electrons after they are accelerated by a known voltage in a vacuum tube or CRT (cathode ray tube, just what you wanted to do, I'm sure).
Electricity and Magnetism: *Magnetic forces, field…. Dipoles. (Sure. Complete sentences.) Derivation of Biot-Savart law. Biot-Savart law = Ampere's law, sort of. Find the field due to a segment of current. Lots of applications use *Faraday's law. You need to be a lawyer to keep track of all these laws. See how Faraday's law is related to EM waves. Find B in or outside any coil. Magnetic flux and electric current conspire to make the current act like it has inertia: *inductance.
To save money in remote areas, power companies can use the earth as a conductor to save on the cost of wires. I have here a remote backscratcher using pipes full of water instead of wires full of electrons to show how this works. I don't yet have much else on alternating current except some advice.
Check out how Britney can digitize her music- learn some stuff about solid state and laser physics at http://www.britneyspears.ac/lasers.htm (It's good physics.)
You may have been a victim of inverse square law abuse, you poor thing. E&M&Relativity might open your eyes a little (then again, it might be good for promoting a little shut-eye).
Here are some simple problems (but not trivial) in magnetism which your physics book will not show you how to do, so don't click on it because you won't be tested on it. Here's how to do 'em. And some harder problems for the computer (to be added later. Here is what I have in mind: We tend to deal with whatever we can calculate in closed form, for example the field due to an infinitely long wire. But infinitely long wires are in short supply in the real world….)
Go to my main mechanics page with links to my junk here and good stuff elsewhere or my main waves page or my main quantum page or look up stuff in my alphabetical index.. Send suggestions, etc. to fredrick.gram @ tri-c.edu (remove spaces) and I will give them full consideration before rejecting them.