Linear Momentum and Collisions. Physics 150/215 Lesson 7 Linear Momentum and Collisions. Definition of linear Momentum Units of Force and Momentum Newtons 2 nd Law in terms of Momentum Law of Conservation of Momentum Collisions Perfectly Elastic Completely Inelastic Center of Mass and Gravity 1

Mass multiplied by Velocity Momentum is defined as Mass multiplied by Velocity 2

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Force = Rate of Change of Momentum D p F = D t This is Newtons second law in terms of momentum ( ) D p D m v m D v F = = = = m a D t D t D t 4

Impulse produced by a force is change of momentum produced by that force 5

Total Momentum of System of many Particles . . e. g. 4 4 å P = p + p p p + + = p Total 1 2 3 4 i i = 1 6

for a closed set of particles Momentum is conserved for a closed set of particles 7

Kinetic Energy is conserved Objects stick together after impact Collisions Perfectly Elastic Completely Inelastic Kinetic Energy is conserved Objects stick together after impact 9

Perfectly Elastic Collision Examples Perfectly Elastic Collision Completely Inelastic Collision

Center of Mass Point is the point where all the mass of a system can be considered to be concentrated Center of Gravity Is the point at which all the weight of a system can be considered to be concentrated 1 0

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P = M v thus D P F = = M a D t Total Total center Total Total Total 1 2