Stuck in Traffic? Pass the Time with Physics

When I find myself stuck in traffic, my mind first turns to the shortcomings of public transit for my typical commute - a part of me wishes I still lived downtown.  The next place my mind often wanders to is physics; a surprising number of seemingly abstract scenarios actually describe the motion (or lack thereof) of one's car in a system of interconnected streets.

One such analogy is that of a system of interconnected springs and masses:

Imagine that you are the sixth car waiting, single file, at a red light.  The moment that the light turns green, the first car begins to accelerate, but you do not move.  Each car must wait for the car in front of them to displace in order to proceed forward.  It is the same for the system of masses.

If a force is imparted on the first mass, there will be a time delay before the effect of this force is felt by the tenth mass.  We can think of the springs like spaces between cars, and the masses as the cars themselves.  This analogy is far from perfect.  For one thing, cars are more independent than this model would suggest.  Car 1 is unaffected by all those behind it, whereas the motion of mass 1 is greatly affected by the motion of those behind it.

High Pressure Situations

A relatively small number of people deal with intense situations on a regular basis.  Overseas military, first responders and ER doctors are part of a select group that deal with high stress on a daily basis.  The rest of us can probably count on one hand the number of traumatic experiences that we have encountered in our modern, sheltered lives.  Personally, I can count this number on two fingers.

The first intense situation that I recall occurred when I was eighteen and living at home.  I started the backyard barbecue, and then went back inside the house while it warmed up.  When I looked back at the barbecue a few minutes later, it was a massive fireball.  I jumped to my feet, and ran towards the fire extinguisher.  As I approached the fire, I was fearful, realizing that the propane tank could have blown up at any moment.  Nevertheless, I sprayed out the blazing flames.

My one and only firefighting experience ended well.    Thinking back now, my actions that evening were instinctive; they involved no thought.  Intense situations do not leave one with much time to think.

Intense situation number two made yesterday a day I would like to forget.