Momentum, product of the mass of a particle and its speed. Moment is a vector quantity; that is, Isaac Newton's second law of motion states that the temporal rate of change of the moment is equal to the force acting on the particle. Moment is a derived quantity, calculated by multiplying mass, m (a scalar quantity), by velocity, v (a vector quantity). This means that the moment has a direction and that direction is always the same direction as the speed of an object's movement.

The variable used to represent the moment is p. The equation for calculating the moment is shown below. The moment of a particle is defined as the product of its mass by its speed. The moment of a system is the vector sum of the moments of the objects that make up the system.

If the system is an isolated system, then the impulse of the system is a constant of the movement and is subject to the principle of preservation of the impulse. Around 530 A.D., working in Alexandria, the Byzantine philosopher John Philoponus developed a concept of impulse in his commentary on Aristotle's Physics. In both frames of reference, any change in momentum shall be consistent with the relevant laws of physics. One of the important properties of the moment and the reason why it is so important in **physics** is that it is a preserved quantity.