1. The problem statement, all variables and given/known data A ball is projected vertically upward with a velocity of 30m/s. It strikes the ground after 8's. 1.1) Determine the height of the building 1.2) Find the height of the ball relative to the ground as well as its velocity at t=3 and t=5 1.3) At what time will its velocity be 25m/s, downward? 2. Relevant equations equations of motion 3. The attempt at a solution 1.1) Okay, I worked out the total time to go up and got 3's and then doubled it for coming down and got 6's (edge of the building). 8-6=2's coming down from top of the building. delta y=vi*t+0.5*a*t^2 height of building = 79.6m 1.2) at t=3's, v=0 delta y = 45.9m Relative to ground: 79.6+45.9=125.5m at t=5's vf = vi+at = 0+(9.8)*5 = 49m/s - 30m/s = 19m/s delta y = 19.6m+79.6 = 99.2m relative to the ground 1.3) vf = vi+at t = 2.55+3 = 5.55's Could someone please check?