How is momentum defined?

Momentum is defined as the product of an object's mass and its velocity. This definition holds importance because it quantitatively expresses how much motion an object has. The concept of momentum takes into account both the speed of an object and how much matter it contains. For instance, if you have two objects moving at the same velocity, the one with greater mass will have more momentum, meaning it is harder to stop or change the direction of that object compared to a lighter one.

This understanding is vital in physics as it describes not just the state of an object in motion, but also how it interacts with other objects, particularly when it comes to collisions and conservation laws. The conservation of momentum principle shows that in a closed system, the total momentum remains constant, which is a foundational concept in both classical and modern physics.