Rotational Motion Find g - Galileo Inclined Plane 1. The problem statement, all variables and given/known data Galileo measured the acceleration of gravity by rolling a sphere down an inclined plane. Suppose that, starting from rest, a sphere takes 1.6s to roll a distance distance of 3.00 m down a 20 degree inclined plane. What value of g can you deduce from this? 2. Relevant equations PE=KE(trans.)+KE (rot.) I=2/5Mr^2 torque=force*distance Torque=I*angular acceleration 3. The attempt at a solution -I've tried to use torque to solve for the acceleration down the plane, and this yielded a=5/7 * g *sin (theta) I used: distance=1/2at^2 to solve for a. a=2.34375m/s^2 When this is plugged back in, I get: 2.34375=5/7 * g *sin (theta) (2.34375*7)/5=3.28125 3.28125/sin(20)=9.59373 g= 9.59373 m/s2 [STRIKE]This is not close to the answer of 9.6, or the accepted value (9.81). I know I'm doing something significantly wrong, but I can't figure out exactly what the problem is. If anyone could point me in the right direction, I'd really appreciate it. Thanks.[/STRIKE] The original problem had to do with an incorrect interpretation of the parallel-axis theorem. It should have been I=ICM+md2.