Worked Problems

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Category archives for Worked Problems

I had an interesting question posed to me recently: how frequently does the sun emit photons with an energy greater than 1 TeV? All of you know about the experiments going on at the LHC, where particles are accelerated to an energy which is equivalent to an electron being accelerated through a potential difference of…

Quick, hit the brakes!

A reader emailed me a fun question from a physics exam he took, along these lines: A car driver going at some speed v suddenly finds a wide wall at a distance r. Should he apply brakes or turn the car in a circle of radius r to avoid hitting the wall? My first thought…

So consider the one-dimensional time-independent Schrodinger equation: In some ways it’s not really an equation as such, because you have to plug in some function V(x) that describes the potential in the problem you’re solving. When you first learn quantum mechanics you’ll learn the big ones: V(x) = 0, V(x) = V > E, V(x)…

A train leaves Cleveland…

The new academic year is starting, and if there’s one thing students love it’s a good word problem. If Sue is four times as old as John will be when Sue is one year than John… So in that spirit I was amused to find basically this kind of problem in a college physics textbook…

Astrology and Gravity

There’s a classic problem in physics textbooks which asks you about astrology. It’s sometimes said – the problem will tell you – that the gravitational pull of the doctor delivering you is stronger than that of Jupiter, therefore it’s unlikely that the planets are exerting a whole lot of influence on your life. The problem…

If you happen to be in the Bryan/College Station area tomorrow, you might consider checking out the Texas A&M Physics Festival. It’s sort of an open house with a ridiculous number of top-notch physics demonstrations as well as some very interesting talks. It’s free! I’ll be there helping out with some of the optics demos.…

First of all, happy Thanksgiving everyone! I hope you spend the day happily with the people you care about, and remember to spend a moment or two reflecting on the things for which you’re thankful this year. Now on with the show: Back when I first started writing this blog, I focused mostly on problem…

I shot an arrow into the air, It fell to earth, I knew not where; For, so swiftly it flew, the sight Could not follow it in its flight. – Henry Wadsworth Longfellow This is what happens when you don’t pay attention in freshman physics. You don’t need to see where the arrow goes to…

A quick contour integral.

Note to the reader: this post is relatively stiff mathematically. For those not mathematically inclined, I think you might enjoy reading it anyway and enjoying it as you would a tour of a widget factory; even if you’re not worried about the details of the nuts and bolts, it’s fun to see it done. While…

Diavolo!

This guy is Allo Diavolo: He was a circus daredevil. At the dawn of the 20th century he worked on a number of stunts dressed in his ominous horned outfit. These days a lot of people, including me, have heard of him as an example in the pages of physics textbooks. In my case it…