1. A 4.5 kg mass is fastened to a light spring, with the intervening cord passing over a pulley as show in the Fig 1. The pulley is frictionless, and its inertia may be neglected. The mass is released from rest when the spring is unstretched. If the mass drops 15.0 cm before stopping, find:
(a) the change in gravitational potential energy of the of the mass.
(b) the spring constant of the spring
(c) the speed of the object when it is 7.5 cm below its starting point
(d) What is the elastic potential energy stored in the spring as the mass reaches the 7.5 cm position?