Input :=
p1d = Plot[ y1[q], {q,0, Pi}]

Output = -Graphics-
Input :=
p1v = Plot[ y1'[q], {q,0, Pi}]

Output = -Graphics-
Input :=
p1a = Plot[ y1''[q], {q,0, Pi}]

Output = -Graphics-
Find the maximum acceleration, which occurs at 90 degrees into the cycle.
Input := a1max = Abs[y1''[Pi/2]] //N
Output = 0.243171
Input :=
p1j = Plot[ y1'''[q], {q,0, Pi}]

Output = -Graphics-