﻿ Momentum & KE

The Heavens Declare His Handiwork

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Momentum and Kinetic Energy
By: Thomas Lee Abshier, ND

Momentum and kinetic energy are both based upon the electromagnetic field associated with particles in a moving mass.  Energy and momentum are conserved in all elastic interactions; that is, in cases where kinetic energy is not converted to other forms of energy such as heat, light, sound, or potential energy (gravitational, electrical or magnetic).  In inelastic collisions, momentum is conserved, and the total energy is conserved.  But, in inelastic collisions, the kinetic energy is converted into other forms of energy, and thus is not available for passing into the target.

The question under consideration is why momentum is conserved, and kinetic energy is not?  The answer seems to lie in the fact that momentum is a vector quantity, and the vector component of momentum is conserved.

Momentum:

p =mv
p = momentum of the mass at a particular velocity
m = mass having a particular velocity
v = velocity of the mass
http://en.wikipedia.org/wiki/Momentum

Impulse:
I = F t = m v = p
I = Impulse, Definition: Impulse = the application of force for a period of time.
F = Force applied (note: equation is only applicable for constant force)
m = mass to which the force is applied
t = time interval over which force is applied
v = change in velocity due to the applied force
p = change in momentum due to change in velocity

http://en.wikipedia.org/wiki/Impulse

Force:

F= ma = m dv/dt  = m d²x/d²t = dp/dt

These concepts of kinetic energy and momentum have been raised to the level of primary phenomena by conventional physical theory.  But, in fact Force is the underlying agent that produces action and the entire range of manifest phenomena.  Kinetic energy and momentum are secondary aggregate phenomena that allow us to engineer and predict based upon these macro concepts.

With the goal of proving this thesis, let us examine the various physical processes involved in rocket propulsion so as to illustrate the connection between Momentum, Kinetic Energy, and Force.  When rocket fuel is burned, it builds up a high pressure inside a combustion chamber.  The high thermal energy of the combustion products is allowed to escape through a nozzle, which directs the molecules of escaping gas in a single direction, thus minimizing back pressure and maximizing their velocity.

The conservation of momentum declares that the momentum backwards equals the momentum forwards, so as to at each moment create a net zero velocity for the center of mass.  Conservation of momentum dictates that the rocket will be thrust forward because of the backwards thrust of the high velocity exhaust products.  The forward thrust of the rocket will occur even in space where there is no stable platform against which to push.

But, the concept that the rocket moves forward because of conservation of momentum is a high level explanation, not addressing the real reason why the rocket ship moves forward.  Conservation of momentum is a useful engineering concept, not a reason why the rocket is thrust forward in response to the combustion products’ backward thrust.

The actual reason for the backwards thrust of the combustion products, and forward thrust of the rocket is the application of Force particles in the forward direction and backward direction.  The generation of force proceeded as follows:

1) Two components of the propellant molecule were bound together with a high-energy bond.  This bond was broken by first raising the molecular internal energy to its activated energy, which is the place where the repulsion of the outer shells of two bonded atoms is equal to attraction provided by the shared electron.  Just beyond this critical separation distance, the repulsion between atoms dominates and the two molecular pieces separate, propelled by this repulsion.  The net kinetic energy released in this repulsive acceleration is greater than the energy used to bring the propellant to the activation energy.  Thus, a net release of energy follows the propellant combustion corresponding to the different of activation energy and kinetic energy released.  That energy was stored in the chemical bonds at the time of the propellant’s manufacture.

2) The Kinetic Energy of propellant combustion is randomly oriented, thus it is measured in terms of Thermal Energy.  But, thermal energy is simply a term used to statistically characterize the average kinetic energy of a large number of randomly moving particles.  This thermal energy can be focused into a single direction via a nozzle, and produce a mechanical thrust.

3) The energy stored in the chemical bonds is stored by supplying sufficient force to move atoms against the repulsion of the outer shells.  The amount of energy required to initiate the formation of a chemical bond is:

activation energy = work = force x distance

Once the activation energy is reached, then the atoms have overcome their repulsion, and are drawn toward each other by the attraction associated with sharing electrons.  In this phase the new molecule releases energy.  The kinetic energy that was applied to the two atoms to produce sufficient proximity so as to be able to bind by sharing electrons is the energy of activation for the chemical bond.  After the atoms are at the place of activation, they are drawn together, accelerate to a velocity, compress bonds, release the compression, expand to the outer limits of the bond, and are pulled back inward.  Thus, an oscillatory vibration of the molecule holds the energy of bonding for a time.  , which in turn causes collisions and transfer of energy to other

To store energy in a highly exothermic bond, such as a rocket propellant, the energy could be supplied to the reactants by placing them in a high temperature and/or high-pressure gas or solution.  These high energy conditions supply the needed activation energy to create the endothermic reaction.  An endothermic reaction requires energy to push it forward to the point where the atoms formed a bond.  Once formed and stable inside the energy well of their bond, they remain in that configuration until the activation energy of a spark or concussion initiates the high-energy exothermic dissociation reaction.

4) As the atoms dissociate with high energy and velocity, they create a high temperature and high pressure combustion chamber environment.  The gasses expand and push out of the nozzle in one direction.  Thus, there is pressure equally distributed throughout the combustion chamber pressing equally on all of its inner surfaces, except the nozzle orifice.  The forces on the rocket are thus imbalanced causing the rocket body accelerate in the direction opposite to its nozzle.  The combustion chamber pressure pushes forward on the rocket body, and because of the deficient corresponding pressure pushing backward on the nozzle orifice a net forward thrust results.

The more perfect the Venturi tube slope of the inlet to throat, and throat to outlet the less the backpressure in the area of the nozzle orifice.  The inward and outward slope of the venturi tube is engineered so as to produce a flow of particles which direct the escaping particles in an axial direction rather than perpendicular to the rocket path.  This corresponds to a minimization of backpressure, which has a corollary effect of maximizing the flow rate of mass through the orifice, which in turn maximizes momentum.  In summary, an imbalance of forces causes the acceleration of the rocket.

Engineers (rocket scientists) use the concept of conservation of Momentum to calculate the force, and thus the force on the rocket during engine burn.  But, we can see from the above analysis that Momentum is not a primary, first principle, or elemental concept.  Rather, Momentum is a second order concept which follows from the primary principles of Force.  Such concepts as momentum are useful for macro analysis of complex systems of particles to engineer systems to calculate the expected effect, but they do not indicate the existence or primacy of another physical principle on the elemental level.