Conservation of Mechanical Energy and Momentum in total inelastic collisions??? In an inelastic collision, such as a bullet getting stuck in a block hanging on a string, has two types of conservations??? -Total Inelastic Collisision Conservations: (1) Conservation of Mechanical Energy: Uo+Po = U + P (2) Conservation of Total Momentum: (m_1)(v_1a) = (m_1 + m_2)*v_b -Questions: 1. Every time (or majority of the time) I am working with a total inelastic collision problem, must I use these two equations or at least consider them first. 2. I read that the conservation of energy is not conserved in total inelastic collisions, then how is it that the total kinetic energy is???? 3. How is the conservation of total momentum conserved??? Is it by taking into the account the initial momentum of the objects before the collision and the momentum of the objects as they are stuck together??? I don't know if I am asking this right. I just want more insight into collisions inelastic/elastic.