With math we proved with math, using KE that a bumble bee going fast enough would develop the energy needed to stop a freight train.
Does anyone really believe that a bumble bee would stop a freight train.
This is a classic example of how taking oversimplifications to an extreme causes misconceptions and misunderstandings about basic physics and what physical quantities mean.
Of course a bumble bee won't stop a freight train. What the calculation did was demonstrate that it is possible for a very tiny and light object going at impossible velocities to generate enough energy to equal the energy of a very large and heavy object going at a more practical (achievable) speed.
Does the fact that two objects have the same energy mean that a head-on collision will bring both objects to a stop? Hardly--just try running forward so that you have a kinetic energy of 500ft/lbs (about 10 mph if you weigh about 180lbs) and have someone shoot you with a .357Mag. It's highly unlikely that either you or the bullet will come to an instant stop although both of you will likely be much the worse for wear after the collision.
Your instructor was not a good instructor if he left you with the impression that the calculation provided a result that was in any way remotely related to anything practical. However, he can be forgiven somewhat since it shouldn't really be necessary to explicitly tell a class of adults that bumblebees can't get up to 5 million miles per hour (what it takes to equal the energy of a freight train) and that even if someone were able to accelerate a bumblebee to that speed, it would instantly burn up due to heat generated by friction with the air.
Ignoring practicalities and assuming that real world issues won't make any difference in the real world will provide nonsensical results.
Of course if you ask an engineer, bumble bees can't even fly.
It's actually quite appropriate for this to come up and I'm glad it did.
http://rationalwiki.org/wiki/Bumblebee_argument
"The "bumblebee argument", in pseudoscience, states that the laws of aerodynamics prove that the bumblebee can't fly, as it does not have the required capacity (in terms of wing area or flapping speed). ...
Unfortunately (for the pseudoscientists), the laws of physics do not in any way forbid bumblebee flight; there are no papers that deny bumblebee flight, and no scientist has done so in a lecture, except, perhaps, ironically. To put it simply, it is possible to "prove" that a bumblebee cannot fly if you perform an extremely crude calculation (like forgetting to take into account things like the rate of flapping, the rotation of the wing, or the action of vortices), but a full aerodynamic calculation (to say nothing of getting all empirical and watching a bumblebee fly) will show that the bumblebee's flight works perfectly fine."
http://www.todayifoundout.com/index...-flight-does-not-violate-the-laws-of-physics/
It's not that scientists/engineers can't explain why/how bumblebees fly, it's that an oversimplified model can provide very misleading results.
No matter what diameter the bullet expands to, for any given diameter you are limited by the inertia of the bullet as to just how deep the bullet will go.
It's ridiculous for you to imply that your misquoting me was in any way similar to my responding to a word-for-word quote from your post. While you rephrased what I said and left out a critical word from my statement, I was, in fact, quoting what you typed directly so there was no chance of a misquote.
Now that you have restated your statement a third time the meaning is finally clear. While the statement is true as far as it goes, it completely ignores the fact that the diameter (in terms of expansion/deformation) is primarily a function of energy and is one of the two main factors that determines how deeply a bullet will penetrate into a given target medium.
In other words, if one pretends energy doesn't exist and doesn't have any effects then, and only then can one make a "reasonable" case for the idea that energy doesn't affect penetration.
The problem is that the ostensible goal is to gain an understanding of what's actually going on--not to support some pet theory that contradicts basic physics. Understanding will not be achieved by intentionally ignoring any of the fundamental quantities of the basic physics of moving objects. Trying to discount, or make light of the science behind terminal ballistics is not going to improve a person's understanding of the topic. While a grasp of basic physics won't give a person all the tools needed to fully understand/characterize terminal ballistics, it's a good place to start.
