MOMENTUM

DEFINITIONS Linear momentum (p) is defined as the product of mass (m) and velocity (v): p = m x v SI-unit of momentum is 1 kg ∙ m ∙ s -1, alternative unit 1 N ∙ s can also be used The change of linear momentum is called the impulse: Δp = F x Δt

LAWS OF MOMENTUM Newton’s second law states, that the resultant force is proportional to the rate of change of momentum: F=(final momentum – initial momentum)/time taken F = Δp/Δt

CONSERVATION OF MOMENTUM The law of conservation of linear momentum states that the total linear momentum of a system of interacting particles (bodies) remains constant provided there is no resultant external force

COLLISIONS Collision in witch no mechanical energy is lost called elastic collision If large amount of energy is lost (as heat or/and sound), but the total momentum is still conserved, the collision called totally inelastic collision. Inelastic collision, in contrast to an elastic collision, is a collision in which kinetic energy is not conserved.

mAmA mBmB v mAmA mBmB v v=0 ELASTIC COLLISION (m A =m B )

mAmA mBmB v mAmA mBmB v/2 TOTALLY INELASTIC COLLISION (m A =m B )

mAmA mBmB v 01 mAmA mBmB v2v2 INELASTIC COLLISION v1v1 p 01 + p 02 = p 1 + p 2 AND K 01 + K 02 = K 1 + K 2 K=1/2mv 2 (KINETIC ENERGY)

FORCE ON GRAPH time/ s Force/ N t1t1 t2t2 F Δp = F x Δt

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