Conservation of Momentum Cheat Sheet
The core ideas of Conservation of Momentum distilled into a single, scannable reference — perfect for review or quick lookup.
Quick Reference
Linear Momentum
The product of an object's mass and velocity (p = mv). Momentum is a vector quantity, meaning it has both magnitude and direction. Heavier or faster objects carry more momentum.
Conservation of Momentum
In a closed system with no external forces, the total momentum before an interaction equals the total momentum after. This applies to all types of collisions and explosions.
Elastic Collision
A collision in which both momentum and kinetic energy are conserved. The objects bounce off each other without any energy being converted to heat, sound, or deformation.
Inelastic Collision
A collision in which momentum is conserved but kinetic energy is not. Some kinetic energy is converted to other forms. In a perfectly inelastic collision, the objects stick together after impact.
Impulse
The product of force and the time interval over which it acts (J = F * delta_t). Impulse equals the change in momentum of an object and explains how forces change an object's motion over time.
Center of Mass
The point representing the average position of all mass in a system, weighted by each object's mass. The center of mass moves as if all external forces act on the total mass concentrated at that single point.
Impulse-Momentum Theorem
The theorem stating that the impulse applied to an object equals its change in momentum: J = F * delta_t = delta_p. A given momentum change can be achieved by a large force over a short time or a small force over a long time.
Recoil and Explosions
When a system initially at rest separates into parts (explosion, gun firing, push-off), conservation of momentum requires the fragments to carry equal and opposite momenta. The lighter fragment always moves faster than the heavier one.
Key Terms at a Glance
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