Conceptual Dynamics - Independent Learning

Impulse and Momentum for Systems of Particles


Linear momentum


The total linear momentum of a system of particles is the sum of the linear momenta of the individual particles making up that system. The linear momentum may also be calculated by using the system's mass and the system's mass center velocity.


G = ∑mivi = mvG


Linear impulse


The total linear impulse is equal to the impulse applied by an equivalent resultant force ∑F applied to the system


I = ∫∑F dt


Linear impulse-momentum principle


The total linear impulse equals the change in linear momentum of the system.


∫∑F dt = ∑mivi,2 - ∑mivi,1


Angular momentum


The total angular momentum of a system of particles is equal sum of the angular momenta of the individual particles. You can also use the position, velocity and mass moment of inertia of the system’s mass center.


HO = ∑(ri x mivi) = rG x mvG + IGω


Angular impulse


The total angular impulse is equal to the sum of the individual force impulses.Note that the forces may act at different locations.


JO = ∫∑(ri x Fi ) dt


Angular impulse-momentum principle


The total angular impulse applied to the system is equal to the change in angular momentum.


∫∑(ri x Fi ) dt = ∑(ri,2 x mivi,2) - ∑(ri,1 x mivi,1)