1. The problem statement, all variables and given/known data A ball is rolled horizontally off the top of a staircase at 1.52 m/s. The dimensions of the steps are 20.3cm by 20.3cm in hight and width, respectively. Which step does the ball hit first? 2. Relevant equations Vector kinematics equations 3. The attempt at a solution At first I tried to make the stairs the slope of a line by using slope 20.3 anywhere on the Cartesian plane and then selected a start point where the projectile motion would begin. I tried to find out an equation for the projectile motion because it's parabolic and then find an intersection point between the parabola and a point on the line, then I'd divide that number accordingly with 20.3 to find which "stair" it hits first. Unfortunately I'm not sure how to transform a vector form into a quadratic equation. Is there any other way to do this?