Linear Momentum - Product if mass and velocity of an object - ⃗ = ⃗ - SI unit: kg*m/s - A vector - The total momentum of a system of objects is the vector sum of the momenta of all the objects - ⃗⃗⃗⃗⃗⃗⃗⃗⃗⃗⃗⃗⃗⃗ +⃗⃗⃗⃗⃗⃗⃗⃗⃗⃗ + ⋯ 1 2 3 Momentum and Newton’s Second Law ⃗ - Ʃ = ⃗ - The net force acting on an object is equal to the change in its momentum divided by the time interval during which the change occurs ⃗⃗⃗⃗ - Ʃ = Impulse - Product of force and contact time - impulse = force * time = F * t - Great force for long time equals large impulse - Same force for short time equals smaller impulse - = ⃗⃗⃗⃗ - SI unit: N*s = kg*m/s - A vector - Impulse and Momentum o = ⃗ = ⃗ o Therefore, the same change in momentum may be produced by a large force acting for a short time, or by a smaller force acting for a longer time. Impulse Changes Momentum - Cases of momentum changes: o Decreasing momentum over a longer time results in smaller force - When a car is out of control, it is better to hit a haystack than a concrete wall. o Same impulse occurs either way, but extension of hitting time reduces hitting force. Conservation of Momentum - The interaction forces