== UNIT 4: LINEAR MOMENTUM AND COLLISIONS ==
Momentum: p = m*v (vector quantity)
Impulse: J = F_avg*Δt = Δp (change in momentum)
Impulse-momentum theorem: impulse = momentum change
Force-time graph area = impulse
Center of mass: x_cm = Σ(m_i*x_i) / Σm_i
v_cm = Σ(m_i*v_i) / Σm_i
Conservation of momentum: Σp_initial = Σp_final (isolated system)
External force = rate of change of momentum
Elastic collision: KE conserved AND momentum conserved
Inelastic collision: momentum conserved, KE NOT conserved
Perfectly inelastic: objects stick together, max KE loss
1D vs 2D: use components for 2D collisions
Explosions: reverse of inelastic collision, momentum conserved
Internal forces don't change center of mass motion