PHYS 121 Lecture Notes - Lecture 22: Beach Ball, Inelastic Collision, Kinetic Energy
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All diagrams taken from "l22_center_of_mass_and_kinetic_energy. pdf" on the course. Quiz: suppose you are to drop two apples from a bridge. A: acm is the same in case 1 and case 2. The acceleration of both objects is -g, therefore the acceleration of the center of mass is -g. Quiz: a boy and a girl are resting on separate rafts 12 m apart in calm water when the girl notices a small beach ball floating midway between the rafts. The boy and his raft have twice the inertia of the girl and her raft. The rafts are connected by a rope, so the girl decides to pull on the rope, drawing the rafts together until she can reach the toy. In isolated systems, the center of mass velocity doesn"t change, so the translational kinetic energy is conserved along with momentum, even if the collision is inelastic or super- elastic.