SUBTOPIC A.2

Apuntes

SUBTOPIC A.2 MOMENTUM AND IMPULSE • What do you think that happens if a car and a byke travelling at the same speed but in opposite direction, crush? Which of them would be more damage? Why? Before starting, let ́s reflect • What if a person falls down when walking or running? Does she/he feel the same pain? Before starting, let ́s reflect LINEAR MOMENTUM The total momentum (p) in a system is the quantity: p = m ∙ v Where m is the mass (kg) and v the speed (m ∙ s -1 ). The linear momentum is measured in kg ∙ m ∙ s -1 - Momentum has a direction (vector) - If speed or mass changes, so does the momentum - A net force leads to a change in momentum (defined by Newton): - 𝑭𝑭 = 𝒎𝒎 � 𝒂𝒂 = 𝒎𝒎 � ∆𝒗𝒗 ∆ 𝒕𝒕 = ∆ ( 𝒎𝒎� 𝒗𝒗 ) ∆ 𝒕𝒕 = ∆ 𝒑𝒑 ∆ 𝒕𝒕 - Kinetic energy and momentum are also linked: - 𝑬𝑬 𝑲𝑲 = 𝟏𝟏 𝟐𝟐 𝒎𝒎 𝒗𝒗 𝟐𝟐 = 𝒑𝒑 𝟐𝟐 𝟐𝟐 𝒎𝒎 CONSERVATION OF MOMENTUM DEFINITION The vector sum of all momenta (plural) remains constant (is conserved) if no external force acts on the system (close system) ELASTIC, INELASTIC, PERFECTLY INELASTIC AND EXPLOSIVE COLLISIONS ELASTIC COLLISION The total momentum...