Assuming nothing else blocks their view, approximately how far can two people stand from each other in clear atmosphere until they can not longer see each other due to the curvature of the earth ? [take : radius of earth = 6400 km] (assume height of each people is 2m) (1) 10 m (3) 1 km (2) 100 m (4) 10 km

22. the top of a cliff is located a distance h above the ground. at a distance h/2 there is a branch that juts out from the side of the cliff, and on this branch a bird's nest is located. two children throw stones at the nest with the same initial speed, one stone straight downward from the top of the cliff and the other stone straight upward from the ground. in the absence of air resistance, which stone hits the nest in the least amount of time?