A solid steel ball is hung at the bottom of a steel wire length 2 meters and radius of 1mm. The ultimate strength of steel is 1.1 X 10^9 N/m^2. What is the mass of the biggest ball the wire can bare. This seems like a pretty straight forward question. I am guessing the 2 meter radius doesn't matter. I am thinking that you need to find the area of a cross section of the 1mm wire. I am not sure what to do next. 2nd part ... what is the period of torsional oscillation of the system? The shear modulus of steel = 8x10^10 N/m^2 and the interia is (2MR^2)/5. Here I think you need to use the equation... T = 2pi * (I/c)^.5 where C is the shear modulus. I can't figure this part out. Do i need to worry about the cross sectional area here also? Thank you very much everyone!