Okay, I am messing something up here. I think it's my logic. Given k=2.5 * 10^3 N/m Find how much mass would have to be suspended from the vertical spring to move it 6.0 cm I get W=1/2kx^2=.5(2500)*(.06m)^2=4.5J I think that's right. Then I do W=F*d=m*a*d or m=W/a*d=4.5/(9.8m/s^2 / .06 m)=7.65 kg But that's not the answer. Help?