Module 2
1. Module 2
1.9. Page 7
Module 2—The Conservation of Momentum in Isolated Systems
Lesson Summary
At the start of this lesson, you were asked the following essential questions:
- Can the complicated details of a linear collision be eliminated during the analysis of an interaction?
- What is the law of conservation of momentum, and how can it be used to answer the previous question?
- Under what circumstances can this law be applied?
When collisions are analyzed in terms of momentum, the complicated conditions that exist during the fraction of a second that the collision occurs do not need to be considered. This approach involves identifying all the objects involved in the system and accounting for the momentum values of each object both before and after the collision.
If there are no external net forces acting on the system, then the system is said to be isolated and the law of conservation of momentum can be used to analyze the collision. This law states that the momentum of an isolated system remains constant:
The law of conservation of momentum is a powerful tool for analyzing collisions. It can be applied to any system that is isolated. In forensic engineering, the systems involving automobiles that crash are not friction-free. Strictly speaking, these systems are not isolated. Nevertheless, if the interaction forces involved in the collision are larger than the frictional forces, then the law of conservation of momentum can still be used to provide reasonably accurate descriptions of the conditions that occurred immediately before and after the crash.
Lesson Glossary
momentum: the product of the mass and velocity of an object