this should be easy but I seem to be getting it all wrong. In constructing a large mobile, an artist hangs an aluminum sphere of mass 5.6kg from a vertical steel wire 0.48m long and 2.5×10−3cm2 in cross-sectional area. On the bottom of the sphere he attaches a similar steel wire, from which he hangs a brass cube of mass 10.3kg . A) Find the elongation in the top wire / Attempt deltaL= (15.9*9.8*.48)/(20e10*2.5e-5) [is this right, I can do the rest]

Question

anonymous · Answer

You failed to convert $cm^2$ into $m^2$ properly. 

$$1m^2 = 10000 cm^2$$ Your cross-sectional area should be $2.5 \times 10^{-7} m^2$