I post here very infrequently, but I'm a high school physics teacher occasionally encountering excellent student questions. Here is one I received today: Since we've been using energy conservation to simplify problems that were annoying earlier in the year (kinematics, mechanics, etc.), can we apply this to projectiles? (Me: yes, definitely, here's some examples...) Particularly, deriving the range formula is annoying, can we do this with energy? (Me: can't think of how...) Also, finding the range of a projectile shot at an angle above the horizontal off a cliff of a known height is really annoying, how about using energy for this? (Me: can't think of how...) Any thoughts, folks?