The Concept

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This website and blog originally started off with an explanation of what kinetic energy is and what it is not. Readers are encouraged to review the discussion in those pages from the very first post.  Only one page of basics will be repeated here, starting with the difference between vector and scalar valued functions when the measurable intensity of the condition of any physical entity is discussed. Key to this is the ability of that entity to perform work or not.

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A vector valued function.  A vector has magnitude (mass), and direction. If it has direction, then by default it is already moving at a certain velocity during any moment of its existence.  Therefore, the physical object that possesses a certain mass and a certain velocity it has the potential to perform work. Merely being in movement does not imply doing any work already - it is only a certain potential of being able to do work. Work is being done only when our entity with momentum moves, or attempts to move something else that has come in its way.

 

In vector valued functions this potential to do work is called momentum - meaning the impetus gained by its mass and its movement.  This impetus is the first and foremost property a bullet in motion possesses - and it is expressed as kilogram.metres/second. (In the whole world only the USA uses the confusing system of feet and pounds avoirdupois to indicate weight and force, and  confusingly - also  energy;   England where it had started has come to adopt the proper International System of Units (SI).

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A scalar valued function.  On the other hand, a scalar variable, or more correctly a scalar field, is a variable that holds only one value at a time, and not more than one (such as a vector function does). It is a single property that we can allocate a number to should we want to quantify the value of that field.  Again - this number is without any direction and neither is it a force. In physics such a scalar field always, every time, only gives a single value for that point and at that moment. (Remember this).  This means that any scalar number by definition says that it is a property in physics measured somewhere on a specific scale that does not have the characteristics to do any work. None. Zero. Zilch. Nada. Nul. Nichts...

 

The one scalar value we all know is temperature - and in this discussion temperature is key:  on a scale of Zero to One Hundred  the "0" indicates when water will freeze and the "100" indicates when it will boil.   Water in the USA freezes at the scalar value of "32" and it boils at the scalar value of "212" . The scalar value "zero" on this scale does not mean "zero" at all; it just is a funny scale with funny scalar values.

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Because temperature is one form of energy (and very important for our discussion: energy is one form of temperature), apart from degrees, in the International units of measurement both energy and temperature are given the same corresponding scalar unit of measurement, namely joules. When the exploding propellant charge in a .308W  combustion chamber reaches its peak pressure the heat of the explosion is 12,000 joules and the energy of the explosion is 3,000 joules.

 

Back to our vector value called momentum or impetus:  The moment that mass had acquired its impetus in the direction it is moving and the potential property to do work, that impetus, because of its movement (kineses) also started absorbing energy-by-kineses. The value of this kinetic energy field at any one time during its movement is expressed in joules - as all energy is.

 

Because all energy is heat, or potential heat and nothing else, the joule value of this energy-due-to-kineses at any one time is exactly the same as the joule value of the heat this moving body will absorb into itself the moment the kineses diminishes or stops.  That is the only thing that happens due to a bullet's built up kinetic energy:  it had a value of joules of potential heat which we could calculate beforehand as it left the muzzle, and that became so many joules of measurable heat into the bullet when the movement slowed down or stopped. Nothing more than this.  No killing ability, no pushing force, no shock, no "ejecting or dumping of energy" into the animal. None. Zero. Zilch. Nada. Nul. Nichts.

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In the strange USA system of measurement this potential heat has been indicated in ft.lbs avoirdupois in rather impressively large figures - and not as joules (or calories, which is also correct).  That has confused rifle and ammunition makers no end.

 

What I really believe is that manufacturers in fact were not confused at all but fully understood the physics.  But: hey, we have hunters who are impressed by superlatives in statements, so for this 130 gr bullet from this here Two-Seventy we'd better not state the vector value of  55 ft.lbs/sec impetus that can actually do the work the bullet must do, so lets hit them with the scalar value of 2,600 ft.lbs of kinetic energy. (Snigger... snigger... we know it is only potential heat but who will complain?  Just imagine telling those buyers we have quite a bit more than a ton impact force!

 

THAT surely made a bigger impact on hunters than on the animals they hunt, did it not.