Phet simulations are simulations on all sorts of topics (not just physics) that come from the University of Colorado - Boulder To find the simulation, either Google "Phet simulation collision lab" or go directly to this link: https://phet.colorado.edu/en/simulation/legacy/collision-lab If the simulation is not working because of Flash, try HTML5 version. Click "explore 1D" part of simulation. Remove thick from "Reflecting Border" Part 1: Elastic Collision-Heavy target a-Set the mass of first object as 0.5 kg and velocity of it as 0.40 m/s. Then set the mass of second object as 1.5 kg and take it as stationary. Then calculate the velocities and kinetic energies of bodies after the collision. (Show it explicitly) b-Perform the simulation and write down the velocities and kinetic energies after collision. c-Calculate the error. Part 2- Elastic Collision- Massive Projectile a-Set the mass of first object as 2.5 kg and velocity of it as 0.40 m/s. Then set the mass of second object as 0.5 kg and take it as stationary. Then calculate the velocities and kinetic energies of bodies after the collision. (Show it explicitly) b- Perform the simulation and write down the velocities and kinetic energies after collision 1 C-Calculate the error.