1. A 10 kg box is sliding along a smooth, frictionless surface at 3 m/s that also happens to be 2 m off the ground below. What is this box’s combined potential and kinetic energy (mechanical energy= Pe + Ke) 2. A ball is falling through the air straight down towards the ground below. The ball is 2.1 kg, is falling at 18 m/s, and happens to be 48 meters from the ground below. What is this box’s mechanical energy? (mechanical energy= Pe + Ke)