Tag «momentum»

Conceptual Understanding in Introductory Physics XXXIV: Parallel and Perpendicular Components of Force

Draw an arrow representing an arbitrary force vector and another arrow representing an arbitrary momentum arrow. Label both arrows. Ask the student to perform the following task: Decompose the force vector into a component parallel to the momentum vector and a component perpendicular to the force vector. Tell whether or not the given force will …

Matter & Interactions I, Week 11

As (almost) usual, I’m writing this on the Monday after the week in question. This week we hit chapter 5, which is packed full of interesting physics and mathematics! We encounter the infamous time derivative of a unit vector (aka a direction), which I have found quite mysterious because of the rather hand waving ways …

Conceptual Understanding in Introductory Physics XXV: A Free Particle?

This question emphasizes geometry and should be done without use of a coordinate system. It should also be done using only symbolic manipulation of vectors. Here it is. Consider a particle moving with a constant, non-relativistic velocity. Starting with a general expression for kinetic energy in terms of either velocity or momentum, prove that the …

Conceptual Understanding in Introductory Physics XX: The Laplace-Runge-Lenz Vector

This post is inspired by the October 2015 AstroNotes in The Physics Teacher. I have sometimes introduced vectors into my introductory astronomy course and students were able to do most of the things described below. We never discussed angular momentum or the Laplace-Runge-Lenz vector, but the other quantities were familiar. I was not permitted in …

Introducing Noether’s Theorem in Conceptual Physics

With little advanced notice, I was assigned a section of conceptual physics to teach this semester (because second semester astronomy was cancelled due to low enrollment and replaced with a section of conceptual physics with the same low enrollment..go figure). After teaching Matter & Interactions for over a decade and after much enlightenment I have …

Conceptual Understanding in Introductory Physics XIII: Differential Equations

This question may very well be beyond the scope of a traditional introductory calculus-based physics course, but given the recent trend in early introduction to computational physics with curricula like Matter & Interactions it may be within the scope of a reformed course. In classical physics, finding a particle’s trajectory under the influence of a …

Conceptual Understanding in Introductory Physics X: Resolving a Vector

For┬áthis post, I decided to ask what I think is a very simple question. It is simple at first, but it also gets to the heart of the meaning of vector quantities, at least as they are typically presented in introductory physics. It also emphasizes the fact┬áthat vector quantities have an existence all their own, …

Conceptual Understanding in Introductory Physics III: Interpreting Physical Quantities

This series continues with a question which, I hope, causes readers and students to reflect on something that is frequently omitted from traditional introductory physics courses. I contend that words are all we have to convey conceptual understanding in physics or any other topic. Yet, in science courses, and especially in physics courses, we tend …

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