Can someone please explain the solution to non constant acceleration kinematics Problem 3 part 3.4?
I think it utilizes the formula x=vt + 0.5at^2. I need some explanation on where Vpo(initial speed) went as well as what y(t) is because if I'm not wrong it is how high above the ground the ipad is, but isn't that already represented by (h-s)?
http://ocw.mit.edu/courses/physics/8-01sc-physics-i-classical-mechanics-fall-2010/translational-kinematics/one-dimensional-kinematics-non-constant-acceleration/MIT8_01SC_problems05_soln.pdf

Question

Can someone please explain the solution to non constant acceleration kinematics  Problem 3 part 3.4?
 I think it utilizes the formula x=vt + 0.5at^2. I need some explanation on where Vpo(initial speed) went as well as what y(t) is because if I'm not wrong it is how high above the ground the ipad is, but isn't that already represented by (h-s)?
http://ocw.mit.edu/courses/physics/8-01sc-physics-i-classical-mechanics-fall-2010/translational-kinematics/one-dimensional-kinematics-non-constant-acceleration/MIT8_01SC_problems05_soln.pdf