50. as a pendulum swings back and forth,
a) potential energy is transformed into kinetic energy
b) kinetic energy is transformed into potential energy
c) at the lowest part of the swing the potential energy is the lowest
d) all of the above are true

Aspring is used to stop a 50-kg package which is moving down a 20º incline. the spring has a constant k = 30 kn/m and is held by cables so that it is initially compressed 50 mm. knowing that the velocity of the package is 2 m/s when it is 8 m from the spring and neglecting friction, determine the maximum additional deformation of the spring in bringing the package to rest.