You are standing on a cliff and kick a rock of the side of the cliff. if it takes 13 secs for the rock to fall to the ground, what was the height of the cliff? do not use a negative value for height of the cliff.

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.