Calculate of velocity `v` of the falling masss P after it has gone down by `x` in an axle and wheel system of radii r and R respectively (Figure 2.12)

[Hint : Let Q go up by `y` when P down by x
Then `(x)/(y)=(R)/(r) :. x=(R)/(r)y`
Apply work-energy theorem to the system (P+Q+ceiling). Remember that the gravitational pulls are the lone forces external to the system, the tensions and pull of ceiling are internal forces of the system]

Answer

`sqrt(2gx(P-(r)/(R)Q)//(P+(r^(2))/(R^(2))Q))`