Momentum What is momentum? ~ Newton’s Quality of Motion Use the 2 nd Law…F = ma to describe how momentum can change when a force acts on it. F=ma m ∆v ∆t Multiply both sides by ∆t : F ∆t = m ∆v ImpulseMomentum

Linear Momentum Linear momentum- the product of mass and velocity of an object. Symbol : pp = mv Units: kg m/s or N s Impulse – the product of the average force and the time interval over which it acts. Symbol: JJ = F ∆t Units: N s or kg m/s

Impulse-Momentum Theorem F ∆t = ∆p (change in momentum) F ∆t = p 2 - p 1 The impulse of an object is equal to the change in momentum it causes. What causes a change in velocity? - an unbalanced force Examples:airbags, egg falling on the floor vs. on a bed

Impulse- Momentum A force applied causes a change in momentum: F ∆t = ∆p F ∆t = p 2 - p 1 So … p 2 = F ∆t + p 1 m 2 v 2 = F ∆t + m 1 v 1 and F ∆t = m 2 v 2 – m 1 v 1

Conservation Of Momentum Closed system – any system that does not gain or lose mass. ***all forces within the system are internal ***all forces outside the system are external Isolated system – the net external force on a closed, isolated system is zero. Law of Conservation of Momentum – the momentum of any closed, isolated system with no net external force, does not change. p initial = p final

Conservation Of Momentum m 1 ∆v = m 2 ∆v When dealing with collisions with before and after scenarios, write an equation for EACH object for the BEFORE and AFTER. m 1 v 1 + m 2 (at rest) m 1 v 1 + m 2 v 2