**In physics, "p equals mv" is the formula used to calculate an object's momentum.** The momentum of an object, represented by the variable p, is equal to the product of an object's mass, represented by the variable m, and its velocity, represented by the variable v.

Momentum is inertia in motion, and inertia is determined by mass and measures the resistance of a body to changes in motion. Momentum is mass times velocity. A stationary object has some inertia, but its momentum is zero. The standard metric units for momentum are kilogram-meters per second. Momentum is also a vector quantity, meaning that it has both a magnitude and a direction.