acceleration/velocity word problem help! The problem is: A hot air balloon is ascending straight up at a constant speed of 7.0 m/s. when the balloon is 12.0 m above the ground, a gun fires a pellet straight up from ground level with an initial speed of 30.0 m/s. Along the paths of the balloon and the pellet, there are two places where each of them has the same altitude at the same time. How far above ground level are these places? I've been stuck on this problem for hours. I started out using the equation d=Vi*t+1/2*a*t^2 for both the balloon and the pellet, then set them equal but I run into problems of where to include the 12.0m at. Ugh...where do I start?