 Having a lower speed or having less mass (how we measure inertia) results in having less momentum. The magnitude of this vector is the final momentum of the isolated system. Galileo in his Two New Sciences used the term "impeto" (Italian), while Newton's Laws of Motion uses motus (Latin), which has been interpreted by subsequent scholars to mean momentum. The concept of momentum in classical mechanics was originated by a number of great thinkers and experimentalists. Conceptually, the momentum of a moving object can be thought of as how difficult it would be to stop the object. Momentum is a conserved quantity, meaning that the total momentum of any closed system (one not affected by external forces, and whose internal forces are not dissipative as heat or light) cannot be changed. Newton's third law of motion, the law of reciprocal actions, which dictates that the forces acting between systems are equal in magnitude, but opposite in sign, is due to the conservation of momentum. The origin of the use of p for momentum is unclear. Momentum is conserved in an electrodynamic system (it may change from momentum in the fields to mechanical momentum of moving parts). In an isolated system (one where external forces are absent) the total momentum will be constant—this is implied by Newton's first law of motion. Massless objects such as photons also carry momentum. That is, the same object may have a certain momentum in one frame of reference, but a different amount in another frame. The principle of conservation of momentum states that the total momentum of a closed system of objects (which has no interactions with external agents) is constant. The momentum of a system of objects is the vector sum of the momenta of all the individual objects in the system. When electric and/or magnetic fields move, they carry momentum. The amount of momentum that an object has depends on two physical quantities—the mass and the velocity of the moving object in the frame of reference. Momentum has the special property that, in a closed system, it is always conserved, even in collisions. Light (visible light, UV, radio) is an electromagnetic wave and also has momentum. Relativistic momentum becomes Newtonian momentum at low speeds.

In physics, momentum is a quantity that can be calculated by multiplying the mass and velocity of the object involved. ... So momentum equals mass times velocity or p = m x v. Therefore, if any object of any mass is not moving, its momentum is zero because its velocity is zero. Examples of Momentum: 1.