Newtons second law of motion Momentum

Any change in the movement of an MP or in its state is caused by the action of other bodies or force fields. The quantitative measure of mechanical action of bodies on another body is called a force. This action can be exhibited as a change in the velocity of a body, or as its deformation. It can be measured in both cases, so the force can be quantitatively evaluated experimentally. 

With the action of the same force on different bodies, their accelerations can be different, depending upon the body s mass. In this instance, mass acts as a proportionality factor between the force, acting on the body and its acceleration. Such mass is identified as the inert mass (unlike the gravitational, which will be discussed below). The mass is a measure of the body s inertial property relative to its translational motion. 

Accordingly, the mathematical expression of Newton s second law can be written in vector form  

This equation is the most general mathematical expression for Newton s second law valid in many cases (for constant and varying masses, relativistic and quantum mechanics). Vector p here equals the product of the body s mass and its velocity and is referred to as the momentum  

In Cartesian reference frames the momentum vector can be expressed as  

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