In physics, the circular motion is described by more than one method, any of them can be used to drive the same equations that govern the behavior of the body in its circular path. Due to these equations, satellites are placed in their orbits, the curvilinear paths are designed with more security such that, cars or trains continue in motion with their high velocities. In the other hand, all these methods failed to describe how the motion of the body is controlled. In addition, they also failed to give reasons why some quantities disappear as if, they are destroyed or balanced. In this research we show that, to describe any motion, the accuracy of the description will be close to the exact one if we use most of the physical quantities that affect the body to control it path. A cording to this method we use the moving body's forces , the side reactions of the body, the centripetal force and the body's momentum to describe the circular motion . As a result we see that, our method can answer most of the questions that the other methods failed to give, and corrects all the mistakes that are considered as scientific evident in the other methods.

The main roles of the side reactions which are created by a body under the effect of an action, is to transmit the effect of the action to all parts of the body and to control the path of the body to follow the line of the action. In this research we show that, the side reactions interfere with the bounding forces between the components of the matter in the body such that, the result is a group of forces that can be called the moving body's forces, or in other words, the interference converts the body to a source of forces that act in the all directions spread out from the body's center of mass. The main role of the moving body's forces is to protect the body from the side effects, but they can be used practically to affect the body itself or anybody without any change in the body's state of motion such that, the conservation of energy law can be violated. Applications show that , if a body is moving under the effect of an action , the instantaneous value of any of its moving body's forces in its direction will not be less than the value of the action whatever the body is state of motion . The values and the roles of the side reactions, and the moving body's forces are stated as the theory of motion.

The theory of motion says that, a body under the effect of an action is converted to a source of independent forces (the moving body's forces) that act in the all directions spread out from the body's centre of mass. The main role of the moving body's forces is to prevent the body from the side effects without affecting the body's state of motion, in this case, any moving body can be seen as a natural energy multiplier. For practical purposes, the motion of the body must be controlled by a system to use at least one of its forces to affect the moving body itself or anybody, but this system must be constructed due to the characteristics of the moving body's forces to get an artificial energy multiplier. In this research we show that, the moving body's forces are used in a curvilinear motion to provide the required centripetal force. That means, the inclined plane in curvilinear motion can be seen as the most simple artificial energy multiplier. The multifunction artificial energy multiplier is a mechanical system in all its parts, designed to use the moving body's forces to do work on anybody without affecting the moving body's state of motion. The power of the energy multiplier is infinite when it is used in its ideal case, and it can increase the performance of any machine that generates mechanical power.

Newton in his third law of motion determined that, anybody under the effect of an action, creates only one opposite reaction at the point of contact between the body and the source of the action. It is clearly that, Newton stated his third law due to the behavior of the body and the source of the action along the line of motion, although applications show that, whenever a body is in motion, there are independent forces appear spontaneously and continuously as if the body is their source to act in the all side directions perpendicular to the line of motion. In this research , we show that , anybody under the effect of an action creates a group of reactions spread out from its centre of mass to act in the all directions , and the reaction which acts in the opposite direction to the line of the action is what we call it the opposite reaction , or Newton's reaction. The effect of the other reactions can be detected clearly from the all perpendicular side directions to the line of motion as real independent forces of the action or the body's state of motion, for that we can call them the side reactions of the body. In this case the side reactions affect the body itself whenever the body is in motion to prove that, the main roles of the side reactions are to transmit the effect of the action to all parts of the body and control the path of the body to follow the line of the action.