Unit 4 · 4.4 — Elastic and Inelastic Collisions

Everything to learn here

• Concept: Linear momentum is conserved in all types of isolated collisions (elastic, inelastic, and perfectly inelastic).
• Concept: Elastic collisions strictly conserve both total system momentum and total system kinetic energy.
• Concept: Inelastic collisions conserve momentum but convert some macroscopic kinetic energy into internal thermal energy, sound, or structural deformation.
• Concept: Perfectly inelastic collisions occur when interacting objects stick together post-impact, sharing a single common final velocity vector and losing the maximum possible kinetic energy.
• Equation: $$m_1\cdot v1i+m_2\cdot v2i=(m_1+m_2)\cdot v_f\text{(Perfectly Inelastic Collision equation)}$$
• Vocabulary: Elastic Collision — An idealized collision in which both total system momentum and total system kinetic energy are strictly conserved.
• Vocabulary: Inelastic Collision — A collision in which momentum is conserved but macroscopic kinetic energy is lost to internal energy or dissipated.
• Skill: Experimental Design (3.A) — Outlining a lab procedure using low-friction mass carts, force sensors, and photogates to experimentally verify momentum conservation and quantify the percentage of kinetic energy lost during a velcro (inelastic) collision.
• Skill: Common Error Avoidance — Never assume kinetic energy is conserved in a collision unless the prompt explicitly states the collision is perfectly elastic.

Practice problems for this topic are coming — generated and validated by our AI pipeline, aligned to these exact items.