Lesson Plan

Distinguish between elastic and inelastic collisions, and identify a perfectly inelastic collision

State that momentum is conserved in all collisions while kinetic energy is conserved only in elastic collisions

Apply m₁v₁ + m₂v₂ = m₁v'₁ + m₂v'₂ to solve one-dimensional collision problems, with correct velocity signs

Apply the perfectly inelastic simplification m₁v₁ + m₂v₂ = (m₁+m₂)v' when objects stick together

Set up a two-dimensional collision of point masses by conserving momentum separately along the x- and y-axes

8.3

"In an elastic collision, the objects separate after impact and don't lose any of their kinetic energy." "An inelastic collision is one in which kinetic energy is not conserved. A perfectly inelastic collision (also sometimes called completely or maximally inelastic) is one in which objects stick together after impact, and the maximum amount of kinetic energy is lost." "$m_1 \vec{v}_1 + m_2 \vec{v}_2 = m_1 \vec{v},'_1 + m_2 \vec{v},'_2$" — conservation of momentum for two objects in a one-dimensional collision; for a perfectly inelastic collision this becomes "$m_1 \vec{v}_1 + m_2 \vec{v}_2 = (m_1 + m_2)\vec{v},'$". "To avoid rotation, we consider only the scattering of point masses—that is, structureless particles that cannot rotate or spin." "Because momentum is conserved, the components of momentum along the x- and y-axes ... will also be conserved."