# How Newton’s Third Law Explains the Conservation of Momentum

The conservation of momentum is one of the most important principles in physics. It tells us that the total momentum of a system of objects remains constant, unless an external force acts on it. But how is this principle related to Newton’s laws of motion, which describe the relationship between forces and motion? In this article, we will explore how Newton’s third law of motion, also known as the law of action and reaction, is the key to understanding the conservation of momentum.

## What is Momentum?

Momentum is a measure of how much motion an object has. It depends on both the mass and the velocity of the object. The more mass and speed an object has, the more momentum it has. Momentum is a vector quantity, which means it has both magnitude and direction. The momentum of an object can be calculated by multiplying its mass and velocity:

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where p is the momentum vector, m is the mass, and v is the velocity vector.

## What is Conservation of Momentum?

Conservation of momentum states that the total momentum of a system of objects is constant, as long as no external force acts on the system. This means that if two or more objects collide or interact with each other, their combined momentum before and after the interaction is the same. The momentum of each object may change, but the total momentum 