In the figure below, a constant horizontal force Fapp of magnitude 17 N is applied to a wheel of mass 6 kg and radius 0.70 m. The wheel rolls smoothly on the horizontal surface, and the acceleration of its center of mass has magnitude 1.00 m/s2. (a) In unit-vector notation, what is the frictional force on the wheel? F=ma , t=I(a/r) 3. The attempt at a solution - I set up both equations with my applied force and frictional force, so I have 2 unknows in my I and frictional force. My problem is coming in not knowing what to sub in for I. I don't know whether a wheel would be considered a solid disc or a hoop. My initial thinking would be I=mr^2, and then I could plug that in into the torque equation and cancel out my r and then solve for frictional force. Would that be correct?