During a physics class on the planet Xoltac, young Greels are asked to determine the gravitational acceleration by using a particle launcher that has a muzzle velocity of 10 m/s. They find that the maximum horizontal range of the particles is 20m. What is the gravitational acceleration on Xoltac? part two: If a Greel were to aim his particle launcher at 60 degrees above the horizontal, what would the range be? I don't see how to find the gravitational acceleration unless the height off the ground from which the particle is shot is known, which it isn't.