1. The problem statement, all variables and given/known data http://i.imgur.com/Osn6pKO.png 2m long Inclined plane. Height at top of the ramp is 6.1cm We are given distances of 0.5, 1, 1.5 2.0m and their times (close to 2.5s, 3.5s ,4.25, 5s). Need to calculate g. 2. Relevant equations d=1/2at^2 g=a/(sinθ/(1+I/mr^2)) (where sinθ=0.061/2) 3. The attempt at a solution So I plotted all the data in excel. Graphed time squared against distance and excel tells me the gradient of that slope is 0.0823, so a is twice that, 0.1646. If I use g=a/sin(theta), 0.1646/(0.061/2) = 5.39 .. pretty far off 9.8. So I assume I have to use the additional info they give me (the diameter of the ball and the V shaped ramp) and add in the effect of the ball rolling. But i'm not sure what formua to use. I thought I/mr^2 for a sphere is 2/5, but then my answer is even further from what I know to be g. Suggestions?