On board: Steve Pollock. x2-2495 F419

Office hours: MW 1:30-3 (+ any time, by app’t)

Steven.Pollock@Colorado.EDU

Reading for next class: Ch. 1 (all), Ch. 2 sections 1, 2, and 3. Also, handout (syllabus)

Today: Intro, Syllabus. (Ch. 1 is your responsibility - background material)

Next: Position, displacement, velocity. (Kinematics)

Welcome! 2010 is an introductory algebra-based course in Physics (and science). It’s about understanding and describing nature. Physics is about things - as versus biological systems, or even chemical systems. How do they move? Why do they move? How do they work?

The world studied by physics looks enormously complicated: CD’s, microwave ovens, moonlight, sunsets, rainbows, flying birds, baseballs, airplanes, asteroids.. You name it!

But beneath this overwhelming chaos and diversity is a remarkable order and simplicity.

This is the main theme of Physics 2010 and 2020 (and all of physics) - seeking out the few underlying simple laws and patterns that let us relate and understand a huge variety of phenomena. It has taken humanity eons to start to sort it out, and the process is still ongoing!

E.g. the patterns you see in a fireworks display, or the shower of sparks from a grinder, the path of a fly ball or an Olympic long jumper... they’re all basically the same simple physics (gravity, and projectile motion) We’ll learn about this already next week.

Physics can be enormously practical and useful, even if you’re not an engineer or physicist. A doctor setting up a complicated traction device working only with uninformed intuition may seriously hurt a patient. Knowing about forces, tension, and gravity may be essential. Physics 2010 is not just about learning physics either - it's also about developing critical thinking and analytical problem solving skills.

It’s very human to be curious about how the world works. We have physics in our genes! Cave people learned it’s a good idea to move if rocks are falling towards you. Clans that spent the time and effort to observe the stars and moon (and correlate them with weather patterns) were surely better able to time and prepare crop plantings. Just watch young kids, they’re enormously curious - Why is the sky blue? What’s a rainbow? What happens if I throw this rock towards that window?...

You must try to find and feed that curiosity in yourself this semester. (Well, o.k., let’s avoid throwing rocks at windows, but... ) Ask why, how do we know this, what is going on, how does this work? I hope you will discover just how fun, cool, interesting and useful physics is.

Surprisingly, the idea of watching and measuring carefully, of creating mental and mathematical models, of experimenting and calculating and comparing - the essential essence of what we call science - is relatively new in the world. 2000 years ago, Aristotle (a Greek philosopher) articulated brilliant, intuitive ideas about how the world works. He was a genius, but he did get a lot of things wrong. His failure to experiment may have been one of the prime factors separating him from modern scientists. (Modern here means maybe 350 years ago or so.)

E.g.: Aristotle observed that objects in motion tend to slow down. He decided that matter has a natural state, which is the state of rest. But it turns out this is not correct - he failed to distinguish between the fundamental, natural motion of objects from the extra complications of friction. Friction depends on speed, material, surfaces, etc. You can reduce it, even (almost) eliminate it if you try hard enough. Galileo (about 350 years ago, i.e. almost 2000 years after Aristotle) experimented with balls rolling on inclines. Those rolling downhill speed up. (The steeper the incline, the faster they speed up, but they always speed up) Those rolling uphill slow down. (Again, the steeper the incline, the faster they slow down, but they always slow down). Galileo asked himself - what about the case right in the middle, with an incline that’s flat (neither uphill nor downhill)? Surely the object will neither speed up nor slow down, but continue along as it was. An object in motion will continue with the same speed and direction, as long as there are no external forces ( like friction) acting on it.

This was the beginning of modern science. Galileo simplified, looked for basic behaviors, separated out complications, experimented, and tested his predictions. And, he turned out to be correct - nowadays we can easily produce ultra-low friction situations, and observe that all objects behave as Galileo predicted. (Afterwards, you can always study friction, and add it back into the story to understand more complicated and realistic motion, but friction is not part of the fundamentally basic and simple story.) Some 50 years later, Sir Isaac Newton (the great hero of Physics 2010!) extended and quantified Galileo’s observations, including the motion of celestial objects as following exactly the same rules.

Believe it or not, 300 years later, most people in the world still function with a worldview that is fundamentally Aristotelian. Some of you may discover (to your chagrin) you have some intuitions about how things move and work that aren’t quite correct, that are not Newtonian. You all have a decent sense of how the world works, of course - you can ride bikes, drive cars, throw balls, use a microwave oven - but when pressed, you’ll discover you have some deep-seated intuitions and conceptions that aren’t always quite right! I’ll try to show you this with demos, exp’ts in the lab, logic, and discussion. One goal for this semester is to help you think about and understand the world in a Newtonian fashion. If you’re serious about a sport (you pick it - running, soccer, climbing, skiing, driving, biking...) I guarantee you that while Aristotle may get you by, Newton will always do you better!! If you’re designing medical setups, setting splints, working on mechanical structures, centrifuging for an experiment.... you must understand how the world really works, or you may be in deep trouble!

Physics 2010 will focus on both qualitative and quantitative understanding. Homework and exams will involve both, too. Lectures will especially focus on qualitative understanding. This leads to an extremely important rule in this course - you must read the material in Giancoli in advance of the lectures. Derivations, problems, and examples are all done in the book, and I’m going to reduce how much repetition of that I do in class. It’s not because they’re unimportant (they’re essential!!) It’s because they’re in the book, and you can all read!

Lectures are for consolidating reading you’ve just done - checking and correcting misunderstandings with the use of Concept Tests and demos. (So, be sure to bring the colored cards to lecture every day. A #2 pencil will be handy too.) Lectures are not going to be presentations and explanations of the fundamental concepts. You will learn those fundamentals before class, from the book! The book will introduce you to terminology and definitions, raise questions in your mind (and quite possibly confuse you) The lectures will help you understand better what you’ve read about, deepen your understanding, and show you how everything fits together.

You’ll do a lot of numerical problem solving in this class, but its not the main focus of lectures. Recitations will focus more on this "plug and chug" style of calculating, and it will be about half of what you do on homeworks and exams. The lectures are about stimulating your thinking and furthering your basic understanding. I guarantee that understanding concepts of physics will improve your problem-solving abilities, but the reverse is generally not true (being able to solve plug and chug problems doesn’t fully demonstrate you understand the physics!)

Please read the syllabus, remember the first CAPA is due this Friday!

As a rule of thumb, you should plan on spending 10-15 hrs/week on 2010, including lectures and lab/recitations. Spending less time will likely diminish your prospects of earning a good grade.

Final comment: I won’t assume a sophisticated math background for anyone (and no physics background at all), but you do need to know a little basic algebra and trig. If you feel uncomfortable, don’t worry. Ask any TA or me for help. Also, you might want to look at Giancoli’s appendix A, for a quick review of most of the essentials.