But, when integrating the acceleration a=dv/dt, then the equation can be expressed.

Integrating the equation (1)

As we see in the equation ( 2), the acceleration a is treated as a constant. The constant a in mathematics and the acceleration a in physics have a very different meanings This is a clearly violation of integral law which must integrate all independent variables dominated by the interval.

Time is a subjective concept. Time like space is useless to argue philosophically. Even though there was an assertion that must choose the initial point ( zero point ) at the moment of creation, it is too absurd to do so.

Even if we decide a standard of time, it cannot be a standard of event dt. Therefore, we should not use differentiation and integration to obtain kinetic energy or work-energy equation. We should reason and understand kinetic energy by the different method.

The momentum formula Ft=mv of object is an absolute formula itself. If we deny this formula, then the theory of motion is impossible to exist. Also, it give births to question how long the momentum can be exist in space. Moreover , it is important how much force is acting on. From this, if we express as equation of how long have the body traveled in space.

(dx/x) is equal to the length of moving object ( the body is practically moving along the spacelength) Substituting L for (dx/d ).

Hence, eliminating the C, we can obtain easily work-energy formula.

(**** Using the formula (1), we can know that Huygens's uniform circular motion is wrong. Until now, physicists has analyzed that v1=v, v2=dv+v in Vector analysis. But this is their wrong understanding. The V1 must be always equal to the V2. If v1 is not equal to the v2, we cannot call it uniform circular motion. If so, V3=v+2dv, v4=v+3dv, V5,V6,............ then we must continuously add the dv. Also. it was his misunderstanding that he analyzed the circular motion with a ball attached to a string . Now,the human beings have known that the circular motion in real space is not attached to a string.

Therefore , the circular motion must be analyzed like the formula (1). * * * We will see this in the next chapter. The question how the planets continue to rotate on its axis and revolve round the sun at the same time is solved by the small rotation angle.

In classic physics, the formula of circular motion could explain only a revolution of planet. I think that the principle of rotation and revolution of all planets are easily understood by this small rotation angle. ***)

The motion of an object has the length of the object in space. Also, relativity theory predicted that the motion of an object produces time-dilation and length contraction. These phenomenon applied to all uniformly moving frames of reference The factor ?derived by the Einstein-Lorentz transformation geometrically proved the time-dilation and length -contraction. This transformation is very complex.

To explain this further, if we use the aberration theory, the factor problem becomes a simple one. When an observer is running with the velocity v, then the time t is longer than the time T . Consequently, the time-dilation phenomenon occurs.

Solving for the length L from Pythagorean' theorem, we get

We can know that its length is less than its rest length.

Every length is contracted in the direction of its motion by the factor. And L is not always greater than 1. This formula proves that the velocity of an object don't faster than the speed of light. Also,the theory of relativity said that the mass of an object increases as the object is moving. In old times, it was main stream that mass is not directly related to the velocity. Geometry did not understand the meaning of mass because the quantity is not geometric property.. But the factor b mathematically proved the change in mass and the observed facts confirmed it.

In classic times, the physicists could not explain how the moving light sources( stars) ,that is , like the sun, emits light . Light is not produced by itself but by matter. Although light is produced by matter, the matter must contain enormous energy. As previously said, many peoples could arrive in the definition of energy by the guess and conjecture.

But Einstein was only a man who was very close to the definition of energy. He declared that rest mass has energy. Before his equivalence equation came out, the physicists could not know the connection between light and matter . His energy formula well explains the connection. But his analysis is very confused.

While solving the problem, the process of obtaining the formula puzzles us. We cannot obtain the new understanding of rest energy and the fundamental meaning of energy because of its difficult processing.

Using the length of general object, L=v/c, v= Lc.

we can write the equivalence equation in other useful form. If we use the length of general object, then the concept of energy, like the rest energy, enormous energy, energy proposed by the theory of relativity, can be easily understood.