Tag «system»

The World’s Most Annoying Negative Sign

TL;DR If you want a quick way to gauge whether or not students understand the concept of potential energy, you can ask them to explain the origin of The World’s Most Annoying Negative Sign. It is merely a consequence of the very definition of potential energy, which is almost never explained coherently. In all of …

Conceptual Understanding in Introductory Physics XXXIII: Drawing Systems

The instructor draw a random diagram showing an arbitrary number of interacting (e.g. gravitationally) entities (e.g. stars, asteroids, etc.) represented as numbered dots. The student is asked to perform the following tasks: Draw a system boundary such that the system experiences a net external force. Name each entity that contributes to this net external force. …

Conceptual Understanding in Introductory Physics XXVI: System Schemas

This question might serve as a final exam for an introductory physics course. It could serve that purpose for my own courses, but it may not be appropriate for your courses so don’t worry if that’s the case. If you do not include system schemas in your course then this question won’t make any sense …

Matter & Interactions I, Week 13

As usual, I’m posting this the Monday after the week named in the title. This week was all about chapter 6: energy and the energy principle. This is where Matter & Interactions really shines among introductory textbooks. I remember as a student being so confused by sign conventions that I honestly never knew when to …

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