A 3.0-m-diameter merry-go-round with rotational inertia 120 kg*m2 is spinning freely at 0.60 rev/s. Four 25-kg children sit suddenly on the edge of the merry-go-round. (a) Find the new angular speed in rev/s. (b) Determine the total energy lost to friction between the children and the merry-go-round in J. Li[tex]\omega[/tex]i=Lf[tex]\omega[/tex]f I=.5mR2 Okay so I know that Li[tex]\omega[/tex]i=Lf[tex]\omega[/tex]f. That means that (120 kg*m^2)(0.60 rev/s)=(mass of merry-go-round + 4(25kg))(1.52)[tex]\omega[/tex]f. To find the mass of the merry-go-round I took the Inertia and divided it by R2 to get m = (120 kg*m2)/(1.52) = 53.3. When I plugged it into the equation I found the new angular speed to be .21 rev/s. My problem is with part (b)... So I know that J is (kg*m2)/s2, but I am unsure as to how to solve for it...A little help, please?