A 54 kg package goes down from the top of a frictionless slide at an initial height of 18 m from the ground. (A) (4) What is the potential energy of the package relative to the ground when it is at the top of the slide? (B) (4) What is the speed of the package when it reaches the bottom of the slide? (C) (4) Suppose the package, upon reaching the bottom of the slide, collides with a 33 kg package, which sits at the bottom of the slide and is at rest. Suppose the 54 kg package and 33 kg package stick together after the collision. What is the speed of the two package ma after the collision