A spool is on a horizontal surface (with friction) and pulled to the right with a thread attached to the center of the spool, so that the spool rolls without slipping. The spool has a mass of M, moment of inertia I, and a radius of R. spool rolling on the floor 1) Which equation below is a correct expression of Newton’s Second Law ( ΣF=ma ) in the x-direction for this situation. Assume all the forces below are magnitudes and that to the right is considered the positive direction.