Water and Electricity Do Mix

*** Disclaimer: Do not wet your finger and plunge it into a live electrical outlet.  The title of this article was intended to be a play on words.  You know what?  If that was not already obvious to you, a severe electrical shock might do you some good.

Some science students are initially baffled when studying electricity.  This is not so surprising, as it is hard to relate to the concept of current, the rate of flow of charge.  The charge that is transported through an electrical circuit is composed of electrons - many of them.  I have never seen an electron, and while I have felt a charge by means of electric shock, I have trouble sensing exactly how many Coulombs are being transferred to me (or are they being taken from me?  I can never tell.).  I have an easier time visualizing, say, mass than I do visualizing charge, and I imagine this to be true for most people.

This is why it is appealing to explore the analogy between electrical current through a circuit and fluid flow rate through a system of pipes.  As a student, I could never remember whether current was constant through resistors connected in series or parallel.  The answer becomes obvious when one considers the flow rate of water through pipes rather than the current through wires.

The Mechanics of Sports Injuries

“Oh crap!!!” is the first thought that runs through your head as you lay on the field/ice/court in excruciating pain immediately following a sports injury.  Whether it is an ankle sprain in soccer, a dislocated shoulder in football, or a broken wrist in basketball, sports-related injuries are painful and frustrating, but unfortunately, inevitable.

The second thought that runs through the injured athlete’s head is, “I wish I could take the last moment back.”  It is an appropriate thought to have, as whenever a collision occurs, the severity of the injury is dependent on just how short the duration of the collision was.  Although impacts in sport between two athletes appear instantaneous, there is actually a small amount of time over which they take place, which we will refer to as dt. 

The Physicist's Guide to Surviving a Montreal Winter

In the sixties, a band called “The Zombies” sang: “It’s the time of the season for loving.”  Now that December has rolled around, it’s the time of the season for freezing if you live north of the equator, and reasonably far from it.  Those of us who actually experience four distinct seasons usually agree that it is good for the soul to see our environment change.  Still, as we dump cat litter under our snow tires before giving the car yet another push, many of us would like to skip over winter.  We curse its arrival every year, and even vacation far from it when the opportunity presents itself.

Winter is very particular.  You can examine a picture of downtown Montreal in mid-February, and know with absolute certainty that you are looking at the winter season.  Snow is the symbol of winter, and after a quarter of a metre of the stuff got dumped on my walkway and driveway last week, I set out at 6:30 am to displace it.