Two right circular rollers (radii, r & R) rest on a rough horizontal plane as shown in the diagram. The larger roller (R) has a string around it with which it can pulled with a force P. Assuming that the coeff. of friction (f) is the same everywhere, determine the condition that the larger roller may be pulled over the smaller roller i.e. show that f>=(r/R)^(1/2). I have tried to draw the FBD but my diagram may not be correct.