And the projectile concepts of the effect of changing potential into kinetic energy and for me to demonstrate my ability to apply elastic potential energy to a scientific investigation.
Since a knowledge of the velocity and projectile construction is essential to evaluating the character of the kinetic energy and its wounding potential, simply relying on a quantity of energy can be quite misleading.
That may seem strange at first, but it has the advantage of giving everything in the universe equal footing.
Regardless of the initial configuration used, the potential energy of a system is equal to the work done by an external force in assembling the system starting from the initial configuration.
For example, let's calculate the gravitational potential energy of the Earth-Moon system. We claim that at infinite separation, the potential energy of the Earth-Moon system is zero. We then find the work done to bring the Earth and Moon together. Once we have that, we have the potential energy of the system.
If we bring the Earth and Moon together from infinite separation to distance , we have
The last two steps show why it is common practice to set (∞) = 0 when great distances are involved—because the potential energy would "naturally" be zero at an infinite separation.
We obtain -7.62×1028 Joules. In other words, to move the Moon away from Earth to an infinite distance through the force of their mutual gravitational attraction, some outside agent would have to insert 7.62×1028 Joules into the Earth-Moon system. This is equivalent to about three minutes and eighteen seconds worth of the Sun's total energy output, or roughly 150 million years worth of the energy consumed by the human population, assuming the global consumption of energy were to remain constant at its 2005 level. 3,4 Potential at a given location is the potential energy per unit mass, sort of a "specific potential energy" if you will. Potential is defined as follows
where m0 is a unit mass.
In the above example, when the archer releases the bowstring, the arrow gets launched when the stored elastic potential energy gets converted into kinetic energy.
Kinetic energy of a body that is not undergoing rotation is given by the following formula:
K = (M × V2) ÷ 2 ----- equation 3
where, 'K' is the total kinetic energy, 'M' is mass of the body, and 'V' is the velocity at which it is traveling.
For a proton, for example, the masses of two up-quarks & one down-quark accounts for only about 2% of the mass and 30% of the spin —showing the considerable contribution of gluons and raw (kinetic & potential) energy(E =mc2) to the total mass and spin of a proton.
This energy is a combination of both kinetic and potential energies of the object, and is characterized by the heat absorption aspect of the atoms, molecules, and other sub-atomic particles.
 For the measurement of the ionization potential, we used a method given by Lenard. In this technique, electrons of a definite kinetic energy determined by the accelerating voltage were sent into a gas-filled space, in which a collecting electrode stood at a potential such that electrons could never reach it, but that positive ions, produced for example by electron collisions, could be collected by it. A positive charging of this collecting electrode was therefore looked on as a proof of the appearance of positive ions. Today we know that the positive charging of the collecting electrode observed in our experiments was caused not by positive ions but by the photoeffect of short wavelength ultraviolet radiation excited by electron collisions. We had thus measured the excitation potential and not, as we believed, the ionization potential. In this error, which was cleared up only after the end of our work together, lies the origin of the mistaken interpretation of our later experimental results.
Sound does not travel in vacuum, i.e., outer space, as compression and rarefaction is not possible in such a medium.
When sound energy is released from an object, the waves spread in all directions, and are a combination of both potential and kinetic energy densities of the body.
For example, if a car passes an observer who is stationary, then the speeds of both objects are relative to each other, and hence the car possesses kinetic energy with a positive value.
 The new insight that in gases without electron affinity electrons are reflected from atoms without noticeable energy loss, as long as their kinetic energy is smaller than the ionization energy (in reality excitation energy) of the gas in question, gave us a new possibility for measuring this so-called ionization energy. For that purpose, nothing more was necessary than to determine the highest kinetic energy at which the electrons are still elastically reflected. With mercury we did not succeed in our earlier experiments to measure the ionization potential using the Lenard method because disturbances arose at the higher temperature that was needed. We therefore decided to use this new possibility for the measurement of the ionization potential of mercury. To that end, we first repeated with mercury vapor the earlier experiments on the noble gases. We used a cylindrical arrangement with an axial filament as electron source. The electrons were accelerated through the mercury vapor by an applied voltage up to a cylindrical wire mesh that is surrounded at a short distance by a cylindrical collecting electrode. By measuring the electron current arriving at this electrode as a function of a retarding voltage applied between the wire mesh and the collecting electrode, the energy distribution of the arriving electrons can be measured. For low accelerating voltages, the expected behavior resulted: In spite of numerous collisions with mercury atoms that the electrons suffered on their way, they arrived at the wire mesh with the full energy corresponding to the accelerating voltage. However, this held only up to a potential of about 5 volts; this magnitude must therefore be the so-called ionization potential. But if, for example, we accelerated the electrons to 7.5 volts, then they arrived with a kinetic energy of about 2.5 eV at the wire mesh. Evidently on their way through the mercury vapor, they had first been accelerated to an energy of about 5 eV, then at one of the next collisions had lost their entire energy, and had been accelerated once again, on the rest of their way, to 2.5 eV, corresponding to the remaining part of the voltage.
Thus, this energy can be simply represented as:
Me = Ep + K
where, 'Ep' is the total potential energy, and 'K' is the kinetic energy.
Numerous modern devices convert other forms into mechanical energy and vice-versa, like thermal power plants (heat to Me), electric generators (Me to electricity), turbine (Kinetic energy to Me), etc.
The conservation of mechanical energy is also dependent on whether two bodies experience collision that is either elastic or non-elastic.