1. The problem statement, all variables and given/known data A golf ball is launched from the roof of a school with a velocity of 20 ms at an angle of 30 deg above the horizontal. 2. Relevant equations If the roof is 40m above the ground, calculate a) the ball's time of flight b)the ball's horizontal displacement 3. The attempt at a solution So for the first question, the example in the book only uses one equation to solve for t, D=v1(t)+1/2a(t)^2,but I thought since the ball goes up and comes down, there should be two separate parts to the solution?