Explanation : When the lift falls, then the gravitational energy changed into the kinetic energy. Gravitational potential is associated with the mass of the lift and its position. When lift starts from rest , the mechanical energy of the lift change in the form of potential energy.
When the lift down than the potential energy lost and kinetic energy is gained. Lift loses height and gains speed.
The work is performed by the lift, when lift covers the distance against the gravitational force.