Physics and Driving

We took our time today and spent some time packing up stuff in anticipation of getting home tomorrow.  Do you know how junky a motorhome can look after two people have lived in it for three months?  We only drove to Monroe, LA, about 210 miles, where we checked into the Ouachita RV Park.  We stayed here our first night on the road almost three months ago.

My thoughts wandered, as usual, as I drove. 

Here Comes Another Rant!

Over the past three months I have driven almost 8,000 miles on a lot of different highways, good and bad.  I have seen a lot of drivers, some of them doing stupid things and endangering themselves and those around them.  I have become very understanding of professional truck drivers for the number of miles they drive and what they have to contend with on the highways.  My motorhome and car combined weigh right at 36,000 pounds and is 62 feet long.  It may not be quite as long or as heavy as an 18-wheeler but it is still much larger and heavier than any automobile.  In a collision you could probably guess which vehicle is going to fare worse.  It’s physics.  When a 4,000-pound mass collides with a 36,000-pound mass, the resulting energy (remember Einstein’s E = MC²?) is going to make mince meat of the lighter mass.  That’s because in a collision there is a transfer of momentum (energy) from one object to another.  For example, at 70 mph the energy of the car would be 4,000 x 70², or 4,000 x 70 x 70 = 19,600,00 (let’s not worry about units) and the energy of my RV would be 36,000 x 70², or 36,000 x 70 x 70 = 176,400,000.  I would give you my 176,400,000 units of energy and you would give me your 19,600,000 units of energy.  My RV has 9 (nine) times more energy than your car.  Who’s going to win?

My motorhome doesn’t have the acceleration of an automobile nor the ability to stop as quickly as an automobile.  My rig requires more time and distance than an automobile to pass another vehicle.  This means that I must practice defensive driving if I am to survive.  I have to be vigilant, observant, and know what is happening in front of and behind me.  I have to watch for other vehicles that may be entering the highway in front of me.  I have to be ready to respond quickly when some other driver does something stupid.  People in cars tend to become impatient and agitated with large vehicles on the highways.  These people are usually traveling faster than the large vehicles and don’t like slowing down or having to wait for an opportunity to pass safely.  That’s when their impatience causes them to do something extremely stupid and injure or kill themselves and/or other people. 

Drivers of automobiles don’t seem to pay nearly as much attention to their driving as do drivers of large vehicles.  They talk and text on their cell phones while driving, play with the radio, or look at the other passengers when speaking to them.  They aren’t aware of their surroundings nor are they attuned to the situations and conditions about them.  Plus, they are not always very courteous.  For example, when a truck or RV puts on its left turn signal to enter the left lane (to pass a slower vehicle or to be in the proper lane for an exit) the automobile drivers in the left lane just keep coming, some will even speed up.  They don’t want the large vehicle to pull out in front of them.  Never mind that the large vehicle will probably be pulling right back into the right lane once it is around the slower vehicle. 

If you are driving at 70 mph and take your eyes off the road for only one second, you will have traveled 102.7 feet without seeing anything over that distance.  In 102.7 feet another car could have pulled in front of you, a deer could have jumped in front of you, a pedestrian could have stepped in front of you, or any number of other things may have happened.  And when you look away from the road, to use your cell phone or play with the radio it is probably for more than one second.  In only three (3) seconds you will have traveled the length of a football field without seeing anything along the way.  Why not just blindfold yourself?

As far as cell phones and driving goes, according to the National Safety Council, one accident per second is occurring in the US.  That’s about 645,000 so far THIS year.  Did you know that as far as cell phone distraction goes, statistics and research have shown there is no difference in using a hand held cell phone or a hands free cell phone.  Distraction is distraction.  Your mind is not on your driving.  You need to get your head back into driving and if you really need to use the phone, pull over and stop.

Back to physics again.  We often speak of deceleration (slowing down).  In physics there is only acceleration.  It can be positive (speeding up) or negative (slowing down).  It’s the negative acceleration that gets you in a collision.  Your body is traveling just as fast as your automobile.  If your car collides with another object, say an immovable object, such as a rock wall, the car comes to an immediate stop.  So does your body.  Like they say, it’s not the crash that kills you.  It’s the sudden stop.  From 70 mph to 0 mph in less than one second will exert a force of 98 g’s (g = force of gravity) on your body.  To put that in perspective, astronauts black out during High g training at 4 – 6 g’s. 

End of Rant

Our journey ends tomorrow.  We only have another 200 miles to go and should be home by lunch.  These past three months have been quite a ride!  I’ll have to go back to the beginning and read the blog to remember all of the places we have been and the things that we have seen.  Those of you who have been kind enough to follow this blog please don’t stop just yet.  I’m not done by a long shot.  Also, there will be more trips coming up.  Stay tuned.