Unit 4 · 4.2 — Change in Momentum and Impulse

Everything to learn here

• Concept: An impulse delivered to an object by a net external force causes a direct change in the object's momentum (Impulse-Momentum Theorem).
• Concept: Impulse is a vector quantity pointing in the same direction as the average applied net force.
• Concept: The geometric area under a Force vs. Time graph equals the net impulse delivered to an object.
• Equation: $$J=F_{avg}\cdot \Delta t\text{(Impulse calculation for constant force)}$$
• Equation: $$J=\Delta p=m\cdot v_f-m\cdot v_i\text{(Impulse-Momentum Theorem)}$$
• Equation: $$J=\int Fdt\text{(Impulse calculated from a variable force)}$$
• Vocabulary: Impulse (J) — The product of the average net force and the time interval over which it acts, equivalent to the change in momentum.
• Skill: Graphical Analysis / Translation Between Representations (1.B) — Calculating the final velocity of an object by determining the exact geometric area under a complex Force vs. Time graph to determine total impulse.
• Concept: Newton’s second law is a direct consequence of the impulse-momentum theorem for systems that maintain a constant mass.

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