1. The problem statement, all variables and given/known data A 250 gram rock is thrown with a speed of 30.0 m/s. It has a speed of 22.5 m/s just before it strikes the ground. Determine the work done by air resistance. There is also a diagram which yields more information. The rocks path is horizontal and it strikes the corner of a box that is 4.60 meters tall, ricocheting the rock at a 25 degree angle. (That is, the ball is projected at a 25 degree angle from a height of 4.6 meters). 2. Relevant equations Ei+Pi=Kf+Pf+(work done by air resistance) 3. The attempt at a solution Kf=63.3J, Ki=113J Pf=0, Pi=? I am having difficulty with the idea of the horizontal path the rock travels and the gravitational potential energy... As well as what exactly to do with the the angle of projection. I understand that I need the initial and final conditions only... but this one is really stumping me. I thank you all in advance for your considerations and help.