Two bodies of mass m₁ and m₂ are connected by an undeformed spring of stiffness k. A constant force F was applied to the body of mass m₁. Due to a small internal friction in the spring, the resulting vibrations were damped. How much has the internal energy of the system increased? What is the final spring energy? If a body of mass m₂ has passed the distance l in the direction of the force F by the time the vibrations are damped, then what is the kinetic energy of the system at this moment?