CP Physics Momentum notes

Momentum Idea of inertia in motion Equation: p = mv, p = momentum, kgm/s Very massive objects moving slowly can have large momentum while very small objects moving extremely fast can have large momentums Ex. Aircraft carrier vs. bullet (Mv = mV) Objects at rest have no momentum

Impulse Impulse = changing momentum – must either change mass or velocity Usually object’s velocity changes Changing velocity requires object to be accelerated – requires net force to act on object

Impulse, part 2 Two factors involved in changing momentum Net force applied - more force = bigger change Time force is applied – longer time = bigger change Impulse = force acting over time to change the momentum of an object Equations: ∆p = m∆v ∆p = F∆t F∆t = m∆v

Changing Momentum Increasing momentum Apply greatest force possible Extend time of contact Largest change in momentum – apply great force over long time Examples – golfer and baseball players following through when hitting golf ball or baseball

Changing Momentum Decreasing momentum – over long time Want to lessen force experienced Extend length of time – will decrease amount of force experienced to less Examples – car safety devices such as airbags, bumpers, padded dashboards, safety nets

Changing Momentum Decreasing momentum – over short time If momentum changes over very short time – then force experienced very large Want very short time if need very large force exerted Example – breaking blocks in karate