1. The problem statement, all variables and given/known data A baseball is thrown from the roof of 21.7 -tall building with an initial velocity of magnitude 13.2 and directed at an angle of 55.0 above the horizontal. What is the speed of the ball just before it strikes the ground? Use energy methods and ignore air resistance. What is the answer for part (A) if the initial velocity is at an angle of 55.0 below the horizontal? 2. Relevant equations PE=mgh KE= 1/2mv^2 KE2=K1+W 3. The attempt at a solution From the prompt I gather that they are suggesting use of the Work Energy Theorem, however, every equation for KE or PE I can think of requires a mass in order to solve for the unknown variable. I've gone over the example my professor did in class, but in both of the examples he had a mass of the particle that was being thrown. I'm not sure how to approach this problem. A suggestion on where to start would be much appreciated. I also think that once I am on the right path I'll be able to get the remainder of the problem completed.