1. The problem statement, all variables and given/known data You're atop a building of height, h, and a friend is poised to drop a ball from a window at h/2. Find an expression for the speed at which you should simultaneously throw a ball downward, so the two hit the ground at the same time. 2. Relevant equations None 3. The attempt at a solution 1)H = vit + 0.5gt^2 t1 = SQRT[(H - vit)/-4.9ms^-2] 2)H/2 = vit + 0.5gt^2 t2 = SQRT[(H/2-vit)/-4.9ms6-2] t2 is the time taken for ball to fall from H/2 to ground t2=t1 so, set t1= SQRT[(H - vit)/-4.9ms^-2] to be equals to t2 therefore, SQRT[(H/2-vit)/-4.9ms6-2] = SQRT[(H - vit)/-4.9ms^-2] vi = [H - 4.9ms^-2(h/2-vit)/(-4.9ms^-2)]/t Could someone give me a let up?