In order to change the momentum of an object, a force must be applied Momentum The time rate of change of momentum of an object is equal to the net force The linear momentum of an object of acting on it mass m moving with a velocity is defined as the product of the mass and the velocity Gives an alternative statement of Newton’s second law SI Units are kg m / s p Vector quantity, the direction of the momentum is the same as the velocity’s t Impulse Average Force in Impulse When a single, constant force The average force acts on the object, there is an can be thought of as impulse delivered to the object the constant force r r r that would give the I = ∆p = F∆t r same impulse to the I is defined as the impulse object in the time Vector quantity, the direction is the interval as the actual same as the direction of the force time-varying force gives in the interval r r r I = ∆p = Fav∆t Impulse-Momentum Where does it show up? Theorem The theorem states that the impulse acting on the object is equal to the change in momentum of the object r I = for a constant force If ∆p is constant, increasing ∆t will reduce Fav If the force is not constant, use the and vice versa average force applied r r r I = ∆p = Fav∆t 1 Deliberately increasing ∆t to reduce Fav Large Fav, Small ∆t Conservation of Conservation of Momentum Momentum, cont Momentum in an isolated system in The principle of conservation of which a collision occurs is conserved momentum states when no A collision may be the result of physical external forces act on a system contact between two objects consisting of two objects that “Contact” may also arise from the collide with each other, the total electrostatic interactions of the electrons in momentum of the system remains the surface atoms of the bodies constant in time An isolated system will have not external forces Specifically, the total momentum before the collision will equal the total momentum after the collision Conservation of Momentum, cont. Mathematically: Momentum is conserved for the system of objects Assumes only internal forces are acting during the collision Can be generalized to any number of objects 2.