[[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:
$$v_f=\frac{m_1v_1+m_2v_2}{m_1m_2}$$
![[Pasted image 20260819112153.png]]
# Elastic Collision Energy Conservation Formula
$$\frac{1}{2}m_1v^2_{1i}+\frac{1}{2}m_2v^2_{2i}=\frac{1}{2}m_1v^2_{1f}+\frac{1}{2}m_2v^2_{2f}$$