1. The problem statement, all variables and given/known data Boxes are placed on a slope at uniform intervals of time trelease and slide down the slope with uniform acceleration. Knowing that as a box B is released, the preceding box A has slid 6 meters down the slope and that 1 second later they are 10 meters apart, determine the following: (a) The value of trelease (b) The acceleration of the boxes. 2. Relevant equations ΔV = a⋅Δt Δx=Vi⋅t+½⋅a⋅t2 2⋅a⋅Δx=Vf2-Vi2 3. The attempt at a solution This problem isn't actually homework, I'm just studying. I'm posting the solution to the problem because I simply don't understand how exactly they arrive at the equations that they do. Here it is: http://i.imgur.com/oSyIFsm.png For example, equation (2) doesn't make sense to me as t = tr + 1, yet in the problem t = 1. Also, how come in eqn. (3) they don't employ the 10 m @ t=tr+1? Why is Δx simply xA@tr+1?