Newton’s second law of motion in terms of momentum states that the net external force equals the change in momentum of a system divided by the time over which it changes In symbols, Newton’s second law of motion is defined to be F net = Δ p Δ t , F net is the net external force, Δ p is the change in momentum, and Δ t is the change time

Impulse, or change in momentum, equals the average net external force multiplied by the time this force acts: Δ p = F net Δ t The conservation of momentum principle is written p tot = constant or p tot = p ′ tot ( isolated system ) , p tot is the initial total momentum and p ′ tot is the total momentum some time later

linear momentum — the product of mass and velocity. conservation of momentum principle — when the net external force is zero, the total momentum of the system is conserved or constant. isolated system — a system in which the net external force is zero. second law of motion — physical law that states that the net external force equals the change in momentum of a system divided by the time over which it changes.