Dowd's Physics Class: General Physics

Welcome to Dowd's Physics Class
The shape of any point source of waves (water, sound, light, etc) is circles moving out from the source

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Old Site Map (from 2019 at MHS)

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This page contains all of the online content for my General Physics course. Dowd keeps all of his content on Flickr, the photo sharing site. Each course has its own album each year. If you click the link to the album, you'll be taken to it. The tables contain the major units in the course. Clicking on these links will bring you to a header photo in the album. To see the course content, scroll forward.

I taught this course at Southmoore, and there are no immediate plans for me to teach it again. I've included it on this website because it's a great overview of physics for anyone looking for the big picture. It's largely based on Paul Hewitt's Conceptual Physics, which has had a huge impact on my teaching generally.
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2015-2016
Southmoore HS

to access the entire album for the course, click here

One Dimensional Motion/Graphing	We explore the meaning of the slopes of (t,d) graphs and introducing the concept of "area under the curve." We also define some important ideas: position, velocity, and acceleration.
One Dimensional Kinematics & Dynamics	A dimension is something that can be quantified using a number line. We'd usually call it "horizontal" or "vertical" or maybe "the x-axis" or "the y-axis." In this unit we study one dimension at a time. We look at the two most common types of motion, constant acceleration and constant velocity motion. That's all the "kinematics" part. The "dynamics" part is where we introduce the concept of force (a push or pull) and go through Newton's 3 laws for dealing with forces.
Projectile Motion	In this unit, we work with motion in two dimensions. It's a relatively minor part of the course, but we'll spend a large amount of time on it, because it's the first topic that requires us to organize our thinking. We'll also introduce what I call the Vegas rule: "what happens in horizontal stays in horizontal, and what happens in vertical stays in vertical."
Momentum	This concept is useful for helping to understand situations where complex forces are acting, forces that increase and decrease during the interaction. We'll see it is especially helpful for collisions and explosions. There are two main topics: first, where momentum is changed by an outside force, and second, where there are no outside forces and momentum remains constant.
Energy	This is the most important unit in the course for helping us be better citizens. It goes through what "doing work" means in physics and discusses what objects or phenomena have the ability to do work. The ability to do work is called energy, and it's the reason energy is so important in our society: if we we want to change our environment, we need energy to do it. It will also be a valuable tool in solving problems that were too difficult to do using the concept of forces.Finally, Power (the "velocity" of energy) is discussed.
Atomic Energy	This is a discussion of radioactivity and radiation, along with a description of the nuclear chain reaction and how nuclear power stations and nuclear weapons are produced.
Circular Motion	Two new concepts are introduced: the centripetal (inward) acceleration that things moving in a circle have to have, and the concept of fictitious forces, which among other things sometimes make us feel like there's a centrifugal (outward) force on us.
Rotational Kinematics and Dynamics	Everything we've been studying up to now moves in a linear fashion: up/down, left/right, in/out and every combination thereof. But what about spinning objects? Fortunately, a parallel and very similar set of rules applies to these. This unit is basically a repeat of the entire course, zeroed in on the specific topic of rotation.
Gravitation and Satellite Motion	This section introduces Newton's Law of Universal Gravitation. It uses this new force combined with the ideas of circular motion to help us understand ideas of planetary motion. A complete treatment of planetary motion doesn't come until later in the year, when we study the concepts of energy and momentum.
Electrostatics	This topic is about how charges can be separated, and how charged objects behave physically. There's a discussion of the electric force (Coulomb's law,) of how much charge an object can hold, and of the electric field, which we'll understand as being very similar to the gravitational field. We'll also discuss lightning and dielectric breakdown
DC Electric Circuits	This unit discusses the kind of electricity that comes from a battery, where charge always flows in one direction. We call the movement of charge current, and since the charge is always going in one direction we call it direct current. Batteries, light bulbs, resistors, and capacitors are discussed. We discuss Ohm's law for determining current in a branch of a circuit and qualitatively mention Kirchhoff's rules.
Magnetism	In this unit, we begin by mapping magnetic fields. We then discuss Orsted's discovery that moving charge causes magentism, and go through a bit of atomic theory to understand how permanent magents are caused by electronic currents in atoms. We talk about the direction of force on moving charged particles and how this enables a DC electric motor to work.
AC Electric Circuits	This unit gets put into the middle of the magnetism unit. Michael Faraday and Joesph Henry figured out in the middle of the 19th century how Orsted's discovery could work in reverse, that is, how magnets could be used to produce electricity. This allowed us to make the generators that supply us with power. The electricity produced by a generator doesn't all flow in one direction, it alternates going one way and then another, so we call it alternating current. This focuses on the amplitude and frequency of AC, how generators work, how transformers work, and how your cell phone charger converts AC power from the wall outlet to DC power for your phone to use. Magnetic braking and how an electric guitar works are part of this unit too. It wraps up with the phenomenon of electromagnetic waves, which are actually light waves, and will be talked about later on.
Simple Harmonic Motion and Waves	This unit is an introduction to repetitive motion. Objects that regularly move back and forth, either linearly or rotationally, are interesting for many reasons, not least of which is that they can be used as clocks. Simple Harmonic Motion is what you get when how hard the object is pulled back is directly proportional to how far away from the midpoint it is. The unit also discusses how something vibrating in simple harmonic motion can force nearby atoms and molecules to do the same, which can force atoms and molecules near them to do the same, creating a repetitive process that makes a travelling wave.
Sound	This unit discusses resonance in musical instruments, "the sound barrier," beat frequencies, and the Doppler effect. This last topic applies to all waves, but it is easiest to understand with sound. There's a discussion here of how we use the Doppler effect with light to do astronomy and predict weather.
Light	This unit discusses light, or electromagnetic waves, which were introduced in the Magnetism/AC unit. It talks about many different frequencies of light, including those we can't see, and what we use them for. It discusses the difference between ionizing and non-ionizing radiation, color blindness, making colors by adding light, making colors by subtracting light, atomic spectra, lenses, why the sky is blue, and polarized sunglasses and 3D movies.