obsidianvault/physics/Linear Momentum/Elastic and Inelastic Collisions.md

Linear Momentum

Summary

• Elastic collision: total kinetic energy stays the same
• Inelastic collision: energy is lost to things like heat and sound
• Perfectly inelastic collision: objects stick together and share one velocity
• Momentum is conserved in every collision where net external force is zero
• "Lost" kinetic energy just transforms into different forms, so total energy is preserved.

Perfectly inelastic collisions:

v_f=\frac{m_1v_1+m_2v_2}{m_1+m_2}

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Elastic Collision Energy Conservation Formula

\frac{1}{2}m_1v^2_{1i}+\frac{1}{2}m_2v^2_{2i}=\frac{1}{2}m_1v^2_{1f}+\frac{1}{2}m_2v^2_{2f}