How does the conservation of momentum apply to collisions?

In the context of physical science, the law of conservation of momentum states that for any isolated system, the total momentum remains constant regardless of internal interactions or collisions.123

Application to Collisions

When two or more bodies collide, the sum of their individual momenta before the impact is exactly equal to the sum of their momenta after the impact. Because momentum is a vector—possessing both magnitude and direction—the momenta of objects moving in different directions can cancel each other out, resulting in a system total that remains unchanged.134

Analytical Utility

Applying this conservation law is often more efficient than calculating the specific forces involved in a collision, as it does not require knowledge of the detailed interaction between the bodies.5

• Elastic Collisions: In these interactions, total kinetic energy is also conserved alongside momentum.64
• Inelastic Collisions: Some kinetic energy is converted into other forms, such as heat or internal energy, yet the total momentum remains conserved.45

By using these principles, physicists can predict the outcomes of collisions ranging from macroscopic objects like billiard balls to subatomic particles.45