ME2120 - Dynamics
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Overview
Professor Ryan C. Cooper reviews Newton’s three laws in ME2120, clarifies where classical mechanics works and where relativity or quantum mechanics is needed, and frames Newtonian mechanics as a model built on cause and effect. The class applies that assumption to a debate about free will, then receives a short individual case-study assignment connecting Newton’s laws, their assumptions, and personal agency.
Key takeaways
- Newton's second law is commonly expressed as F = ma when mass is constant, while Newton's original formulation relates force to changes in momentum.
- “Non-Newtonian” describes a fluid's non-proportional relationship between shear stress and flow rate, not a failure to obey Newton's laws of motion.
- Classical mechanics is a practical model for ordinary objects and speeds, but quantum mechanics and relativity are needed at very small scales, extreme masses, or near-light speeds.
- Using Newtonian laws as a predictive framework assumes that events can be explained through causes and effects, which motivates questions about determinism and free will.
- Chaos theory shows that deterministic rules can generate complex, hard-to-predict outcomes, so unpredictability alone does not establish randomness or free choice.
- The assigned case study asks each student to connect Newton's laws and their assumptions to personal agency in a short, roughly hour-long response.
Chapters
- Ryan C. Cooper outlines a four-day break and says the class will resume the following Wednesday.
- HuskyCT contains the syllabus, course introduction, Newtonian mechanics reading, and the first case study.
- The first case study is due on the 10th, and Cooper plans to complete the semester schedule by the next class.
- Students identify inertia: an object's state of rest or motion does not change without a net force.
- Cooper links force to acceleration through F = ma, noting that Newton's original formulation described force as changing momentum.
- Newton's third law pairs every applied force with an equal and opposite reaction force.
- Cooper distinguishes Newtonian mechanics from Newtonian fluid behavior: non-Newtonian fluids still accelerate when forces act on them.
- A Newtonian fluid's shear stress is proportional to its flow rate, while non-Newtonian fluids can have more complex stress-flow relationships.
- Silly Putty illustrates shear-thickening behavior: it deforms slowly but can bounce when struck quickly.
- For rigid-body dynamics, the course treats forces as inputs, whether they come from gravity, springs, fluids, or electromagnetism.
- Newtonian mechanics remains useful for everyday objects, from cats to tanks, but not for every scale or speed.
- Quantum mechanics is needed for very small systems such as electrons, while general relativity matters for extremely massive systems and intense gravity.
- At speeds near 99% of the speed of light, F = ma alone is inadequate and relativistic effects must be considered.
- Satellite orbits can shift because of their initial conditions; operators may correct the orbit or leave the satellite as space debris.
- Cooper asks what baseline assumption makes Newton's three laws work as a problem-solving framework.
- The class identifies cause and effect: events are treated as consequences of prior conditions rather than unexplained randomness.
- Cooper illustrates the chain-of-causes idea with a person sitting in class, connecting prior events, bodily processes, and forces to the present state.
- Students consider whether free will can exist if every action follows from prior causes under Newtonian mechanics.
- Cooper invites students to argue for or against free will and to post a vote with a written reason.
- The activity is framed as an open philosophical question rather than a problem with a single settled answer.
- Students submit votes and discuss whether a person can retain free will while facing external constraints, such as imprisonment or coercion.
- Cooper notes that the class's definition of free will varies, making a simple yes-or-no vote difficult to interpret.
- The discussion distinguishes having a choice from being able to express that choice freely.
- Cooper estimates that about 55% of the class supports free will and 45% rejects it.
- Students argue that complex outcomes may seem to imply choice, while deterministic rules can also produce complexity.
- Cooper uses chaos theory and Jurassic Park's phrase “life finds a way” to illustrate how simple rules can lead to difficult-to-predict outcomes without requiring randomness.
- The assignment asks students to explain Newton's laws, identify their assumptions, and consider whether those laws constrain people or serve as a useful tool.
- Students may submit a paragraph or bullet points, either as a document or directly through the course platform.
- The work is individual, builds on the class discussion, and should take about an hour rather than becoming an overlong paper.
- Cooper says older course-overview items such as quizzes and Jupyter notebooks are not part of the current plan.
- Course discussions and schedule updates will be managed through HuskyCT, with the schedule kept current as plans change.
- Newton's laws are intended to model the real world, but the model has limits and does not capture every physical phenomenon.
- Cooper describes an existentialist perspective in which being involves more than a chain of causes, contrasting a rock's motion with a person's ideas about becoming something new.
- The class briefly considers whether determinism should change how society punishes people, since actions may have prior causes.
- Cooper explains that individual honors conversions have been difficult to support without dedicated teaching-assistant resources, especially as enrollment grows.
- The closing discussion also raises a third position on free will: that the question may not be knowable.
Transcript excerpt
1:16 All right. Okay, we made it back. Hey, welcome back. Day two and then plan is take a little break. Actually, a 4-day weekend break because we'll take Friday off at least from this class and then we'll be back on Wednesday. So, in another week. So, we got seven days to just sort of like take in and kind of process whatever we do today. Sound like a plan? No issues so far? Still early, right?
2:08 Issues come up. They'll keep coming up. Cool. Uh so right now HuskyCT has um our syllabus module zero like getting started uh philosophy of this Newtonian mechanics and then our first case study which is based on so we're just going to spend one class on this to practice talking to each other practice thinking about problems and this kind of thing and then you'll turn that in uh next week on the 10th. So in a week, so a week and a day from now and then I'll keep add then I'll add more case studies and the projects. So the rest of the semester will get planned out within as
2:56 uh by time we get back here next Wednesday, we'll have all that planned out. Still no issues. I'm looking for like uh yes, so many issues Nothing yet. All right, we're on track then. All right, so did you read about the dogmatism in Newtonian mechanics? It's pretty it's a short read, so even if you didn't, you can be like, I read it and like quickly you can skim Let's let's get into this a little bit
3:44 because it's a nice review of what do we know? What can what are we assuming? And then also where does that lead us to? Want this guy down here up there.
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Summary, takeaways, and chapters were generated by AI from the video's transcript and may contain errors. The video belongs to its creator, Professor Ryan C. Cooper.