1. The problem statement, all variables and given/known data A boy throws a rock off of a cliff that is 33m high. The rock weights 1 kilogram and it's inital velocity is 13.5m/s. It is thrown at an angle of 40° with the horizon. Initial Velocity = 13.5m/s mass = 1 kg θ=40° Δy = 33m g = 9.81 m/s^2 2. Relevant equations Potential Energy (Joules) = Ug = mgy Kinetic Energy (Joules) = K = .5(m)(v^2) 3. The attempt at a solution Calculate the velocity of the rock just before it hits the ground at bottom of cliff. No heat is generated--assume ideal conditions. Potential Energy -> (Ug = mgy) = (1kg)(9.81m/s^2)(33m) = 323.4J Kinetic Energy -> (K = .5(m)(v^2) = .5(1kg)(13.5m/s^2) = 91.125 J This is where I get lost, I don't understand how to solve for the END velocity. I also didn't incorporate anything with the angle...I just feel lost and I would greatly appreciate assistance.