A uniform solid sphere of mass M and radius R rolls, without slipping, down a ramp that makes an angle θ with the horizontal. The question ask for me to find the force of friction between the ramp and the sphere. My attempt at the problem was to utilize the x-component of the force of gravity of the sphere and then the friction must be greater than that component. I also have a feeling to use final energy - initial energy = nonconservative work, but I can't seem to find a velocity, whether its linear or angular, which is necessary to find the energy. Note: when a ball rolls without slipping, v=R * [tex]\omega[/tex] Thank you for your time.