What is the definition of momentum in physics?

Momentum in physics is the product of an object's mass and its velocity.

In more detail, momentum is a fundamental concept in physics that describes the motion of an object. It is a vector quantity, meaning it has both magnitude (size) and direction. The momentum of an object is calculated by multiplying its mass (how much matter it contains) by its velocity (how fast it is moving and in what direction). The unit of momentum in the International System of Units (SI) is kilogram meter per second (kg m/s).

Momentum is always conserved in a closed system, which is a key principle used in the study of collisions and explosions, known as the law of conservation of momentum. This law states that the total momentum of a system of objects is constant if no external forces are acting on it. For example, in an isolated system where two objects collide, the total momentum before the collision is equal to the total momentum after the collision.

The concept of momentum is also crucial in understanding Newton's second law of motion, which can be stated as 'the rate of change of momentum of an object is directly proportional to the force applied'. This means that if you apply a force to an object, you will change its momentum. If the force is applied for a longer time, the change in momentum will be greater.

In summary, momentum is a key concept in physics that describes the motion of an object. It is calculated by multiplying an object's mass by its velocity, and it is always conserved in a closed system. Understanding momentum is essential for studying the laws of motion and the behaviour of objects when they collide or explode.