A helical compression spring is made out of 5mm diameter music wire with a modulus of rigidity of 70 GPa and 16 active coils. What should the diameter of the coils be to have a spring rate of 8 N/m

The anwser is: wave a has a greater pitch and frequency.

Ke reqd to move from 0 to 50 will be proportional to 50x50 or 2500. this is equal to w.  to change vel from 50 to 150 you need energy prop to 22500 - 2500 = 20,000. this corresponds to 8w.  best answer is a) . work reqd is prop to velocity squared.