1. The problem statement, all variables and given/known data A 75 g 30 cm long rod hangs vertically on a frictionless, horizontal axle passing through its center. A 10g ball of clay traveling horizontally at 2.5 m/s hits and stick to the very bottom tip of the rod. To what maximum angle measured from the vertical, does the rod with attached ball of clay rotate? 2. Relevant equations Angular momentum is conserved initial L=final L mvr=Iω I=1/12MR^2 +mr^2 rotational K.E=1/2 Iω^2 MGh 3. The attempt at a solution angular momentum : 0.01(2.5)(0.3)=(I1+I2)ω Rod: I1=1/12MR^2=1/12(0.075)(0.15)^2=1.40e-04 Clay: I2=mR^2=.01(0.15)^2=2.25e-4 Initial energy =1/2 (I1+I2)ω^2 h1=.3-.3cos∅ mgh1=.01(9.8)(.3-.3cos∅) h2=.15-.15cos∅ Mgh2=0.075(9.8)(.15-.15cos∅) Final energy=Mgh1+mgh2 my question is only kinetic rotational energy is converted to potential energy and how come the kinetic energy is not converted to rotational energy and my teacher said the linear momentum is not conserved and I am so confused . Secondly, why the mass of initial angular momentum is small mass not the mass of clay and rod ?