I am still stuck with this problem. Please, help if you can. A large, cylindrical roll of tissue paper of initial radius R lies on a long, horizontal surface with the outside end of the paper nailed to the surface. The roll is given a slight shove (V initial = 0) and commences to unroll. Assume the roll has a uniform density and that mechanical energy is conserved in the process. Determine the speed of the center of mass of the roll when its radius has diminished to r = 1.0 mm, assuming R = 6.0 meters. This is what I got so far. KE=(1/2)I(Omega)^2 for the cylinder I is :(1/2)MR^2 So mgh=(1/2)I(Omega)^2+(1/2)mv^2 I plugged in I mgh=(1/2)(1/2)MR^2(Omega)^2+(1/2)mv^2 Then I used (omega)=v/r to get here mgh=(1/4)MR^2(v/r)^2+(1/2)mv^2 the masses cancel gh=(1/4)R^2(v/r)^2+(1/2)v^2 Now what? How do I get h? Did I miss anything? Thank you in advance!!