1. The problem statement, all variables and given/known data the question says " when did the rock reach half its maximum height? 2. Relevant equations a rock is thrown vertically upward from the surface of the moon at a velocity of 24m/sec and reaches height of s= 24t-0.8t^2 3. The attempt at a solution i figured out when the rock reaches max point which is 15 seconds. i think when velocity = zero is when you can figure out the max height. i don't know about half of max height.