Conservation of momentum principle

Definition

The principle of conservation of momentum states that the total linear momentum of an isolated system remains constant if no external forces are acting on it. This means that the momentum before and after a collision or interaction is the same.

5 Must Know Facts For Your Next Test

1. Momentum is a vector quantity, having both magnitude and direction.
2. In elastic collisions, both kinetic energy and momentum are conserved.
3. In inelastic collisions, only momentum is conserved; kinetic energy is not necessarily conserved.
4. The mathematical expression for conservation of momentum is $\sum \vec{p}_{initial} = \sum \vec{p}_{final}$.
5. External forces can change the total momentum of a system, but internal forces cannot.

Review Questions

• What does it mean for momentum to be conserved in an isolated system?
• How does conservation of momentum differ between elastic and inelastic collisions?
• What role do external forces play in the conservation of momentum?

Related terms

Linear Momentum: A measure of an object's motion given by the product of its mass and velocity ($\vec{p} = m\vec{v}$).

Elastic Collision: A type of collision where both kinetic energy and momentum are conserved.

Inelastic Collision: A type of collision where only momentum is conserved, but some kinetic energy is converted into other forms of energy.