1. The problem statement, all variables and given/known data Four identical balls are thrown from the top of a cliff, each with the same speed. The first is thrown straight up, the second is thrown at 30° above the horizontal, the third at 30° below he horizontal, and the fourth straight down. How do the speeds and kinetic energies of the balls compare as they strike the ground… when air resistance is negligible? when air resistance is significant? 2. Relevant equations Eg = mgh, Ek = 1/2mv^2 Et = Ek where height <= 0 Et = Eg where height > 0 3. The attempt at a solution Eg = mghcos()?