Final answer:
In the collision where the particles trade momentum, 4mp^2 of kinetic energy is lost. In a completely inelastic collision, 6mp^2 of kinetic energy is lost.
Step-by-step explanation:
In the given scenario, the particles collide and trade momentum so that particle 1 has momentum of magnitude p and particle 2 has momentum of magnitude 2p. The question asks how much kinetic energy is lost in the collision. To find the kinetic energy lost, we need to compare the initial kinetic energy before the collision with the final kinetic energy after the collision.
Before the collision, the kinetic energy is given by 0.5 * m * (2p)^2 + 0.5 * 2m * p^2 = 6mp^2. After the collision, the kinetic energy is given by 0.5 * m * p^2 + 0.5 * 2m * (2p)^2 = 10mp^2. Therefore, the kinetic energy lost in the collision is 10mp^2 - 6mp^2 = 4mp^2.
In the case of a completely inelastic collision, the two particles stick together after the collision. In this case, all of the initial kinetic energy is lost. So, the kinetic energy lost is 6mp^2.