1. The problem statement, all variables and given/known data "A solid sphere rolls down an incline plane without slipping. If the center of mass of the sphere has a linear acceleration of 1.21 m/s2, what is the angle of the incline to the horizontal?" 2. Relevant equations a = g * sin(θ) 3. The attempt at a solution I got home from a long day at work and can't seem to make my mind click on how to solve this problem. What's throwing me off is that the linear acceleration is given in m/s2, but when I googled some similar problems to this one and they all give the linear acc. in 'g'. I think I need mass but I can't figure out how to get it or if I'm even correct. Can someone help me? Am I over-complicating this, or am I just being incredibly stupid. :( Brain doesn't want to work.