External force

Definition

An external force is any force that originates from outside a system and acts on the objects within that system. It can change the motion of the objects by altering their velocity or causing deformation.

5 Must Know Facts For Your Next Test

1. External forces are responsible for changes in momentum of a system.
2. Newton's Second Law, $F=ma$, describes how an external force affects an object's acceleration.
3. External forces can be contact forces (e.g., friction) or non-contact forces (e.g., gravity).
4. The net external force acting on a system is crucial for determining the motion of the center of mass.
5. In collisions, external forces determine whether momentum and kinetic energy are conserved.

Review Questions

• What distinguishes an external force from an internal force?
• How does Newton's Second Law relate to external forces?
• Why are external forces important when analyzing collisions?

Related terms

Internal Force: A force that acts between components within a system, affecting only the internal structure without changing its overall motion.

Net Force: The vector sum of all forces acting on an object or system, determining its acceleration according to Newton's Second Law.

Center of Mass: The point in a body or system where its mass is evenly distributed and about which it will balance under the influence of gravity.