I did an experiment where I had to determine the static friction of a wooden block on a horizontal wooden plank. I determined Mu s for that to be 0.246 I then used the same block and plank, but this time I tried to determine Mu s by increasing the angle between the plank and the horizontal. I basically raised one side of the plank until the block started sliding...and recorded that angle as the angle of repose. I got Mu s for this part of the experiment to be 0.306 now I had to calculate the percent difference: ((.246-.306)/average) * 100 and I got 21.69 % Shouldn't the percent difference be as small as possible? I assumed that Mu s would theoretically be the same no matter what angle?