Category Archives: physics

Rolling without slipping on curved surfaces

Posted on December 31, 2022 by Andy Rundquist

I’ve been trying to see if I can model balls rolling on curved surfaces and I think I’ve cracked it. Here’s a teaser to get you interested: What you see is a sphere rolling on a curved surface. The blue … Continue reading →

Posted in fun, general physics, mathematica, physics | Leave a comment

Situations that share equations of motion

Posted on December 9, 2022 by Andy Rundquist

Recently my friend Rhett Allain has been making some awesome videos showing how to solve complex problems with a Lagrangian approach. I love it when he posts a new video because it usually motivates me to try to model something … Continue reading →

Posted in mathematica, physics | 3 Comments

Rigid bodies, formulation and examples

Posted on November 25, 2022 by Andy Rundquist

My friend Rhett Allain gave me a good challenge recently with this tweet: I had been working on a problem that he posted about regarding a bead sliding freely on a hoop that is spinning about an axis in its … Continue reading →

Posted in mathematica, physics, syllabus creation, teaching, twitter | 1 Comment

Brachistochrone for rolling things

Posted on March 19, 2022 by Andy Rundquist

The Brachistochrone curve is the shape of a wire for beads to slide down (friction free) to get from point A to point B the fastest. Note that since I used the word “down” there I’m implying this happens in … Continue reading →

Posted in math, mathematica, physics, teaching | 3 Comments

Catenary with Lagrange Multipliers

Posted on January 24, 2021 by Andy Rundquist

The catenary is the shape of a hanging chain supported at both ends in a constant gravitational field (ie normal life). Recently Rhett Allain has been doing some great work using both python and analytical results to show how you … Continue reading →

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Physics Teachers Are Awesome

Posted on December 23, 2020 by Andy Rundquist

I’ve started a project that brings me joy. I’m hoping to help spread that around! I was looking around for ways that I could support physics teachers who were working so hard to teach during this pandemic. I was reflecting … Continue reading →

Posted in glodal physics department, online class, physics, screencasting, syllabus creation, teaching, twitter | 4 Comments

Boltzmann to Blackbody to Electoral College

Posted on November 15, 2020 by Andy Rundquist

Ok, I know that’s a weird title, but bear with me, this has some fun stuff in it, including some things I still need help with. The basic idea is that Planck’s solution to Blackbody radiation is an interesting way … Continue reading →

Posted in physics, programming, teaching | Tagged , , | 1 Comment

Fast Quantum Tunneling Method

Posted on August 15, 2020 by Andy Rundquist

This post describes a way to calculate tunneling probabilities for one dimensional quantum barriers. This method is easy to code up, and is very fast. Consider the following barrier. If your energy is less than 3 eV, you’ll just reflect … Continue reading →

Posted in mathematica, physics, research, teaching | Leave a comment

One die to rule them all

Posted on January 16, 2020 by Andy Rundquist

For a number of years I’ve been working on finding ways to turn what looks like an unfair die to a fair one (see these posts). Recently I’ve made a lot of progress. This post shows how I’ve turned a … Continue reading →

Posted in fun, mathematica, physics, research | 4 Comments

Shooting circuits

Posted on June 27, 2019 by Andy Rundquist

I’ve posted before about how I struggle teaching complex circuits (really just circuits that contain batteries and resistors in ways that can’t be analyzed with parallel and series tricks). There you’ll read about how I find that if I just … Continue reading →

Posted in general physics, physics | 8 Comments