The thoughts that were thunk and the goings on of my life.

Wednesday, September 14, 2005

Speed Kills

People seem to think it's speed that kills. While arguments could be made for that statement, speed is not what actually kills. In this post I would like to argue that it is not speed that kills; rather, it is Kinetic Energy that kills.

Let's take a look at Speed and see what happens with with objects going at the same speed of 70 miles per hour (~115 kph) and a person's reaction to each.
  1. June Bug - Ow, what the heck was that? Stupid bug. Squish.
  2. Baseball - I'm gonna kill you pitcher...wait, you wrestle steers for fun, oh crap.
  3. Suburban - You think nothing because you are dead.
Notice the difference in the reactions? The reactions are different because it is not speed that kills, it is kinetic energy.

Let's now take a look at the kinetic energy of these objects. (KE = 1/2 * m * v^2). Where 70 mph = 31.3 m/s.
  1. June Bug - m = 1/5 oz = 0.005 kg; KE = (0.005*31.3^2)/2 = 2.44 Joules
  2. Baseball - m = 5 oz = 0.15 kg; KE = (0.15*31.3^2)/2 = 73 Joules
  3. Suburban - m = 8600 lbs = 3900 kg; KE = (3900*31.3^2)/2 = 1,900,000 Joules
As you can see the real killer in the world is Kinetic Energy, not speed. So, let's move on to the crux of the whole issue. Let's take a look at speed limits. Everybody knows that speed limits are in place to save lives. But as we've just proven speed is NOT what kills, it's Kinetic Energy.

Instead of Speed Limits they should place Kinetic Energy Limits on our highways to keep the populace safe! That way we could make sure to put a curb on unnecessary deaths.

Let's say that the limit on the state highways is 2 million Joules. Sounds reasonable. Now think of how much fun it would be to have 2 million Joules while on my motorcycle!

Where: m = 700 lbs = 320 kg, v = x m/s, KE = 2,000,000 Joules
Solving for v we get:
v = sqrt(2*KE/m) = sqrt(2*2000000/312) = 113 m/s

What does all of that mean? It means that under proper laws I should be allowed to go 253 mph when I'm on my motorcycle! Now that sounds like a good time!

*this train of thought courtesy of David Harding*

1 comment:

Anonymous said...

Wow, would that ever piss off the teamsters. I'm lazy so I won't work the math, but an 18 wheeler carries a *lot* of kinetic energy.