The maximum applied force of compression of one man's thighbone can endure without breaking is 7.0 x 104 N. The maximum effective cross-sectional area of the bone is 4.0 x 10-4 m2 , its length is 0.55 m, and Young's modulus is 9.4 x 109 N/m2 . The mass of the man is 65 kg. Based on this maximum applied force of compression, a change of length of DL = 0.01 m was determined for the thighbone just before breaking.

(a) Assuming the thighbone is an elastic material, what is the work needed to compress the thighbone by DL = 0.01 m?

(b) Assuming the man falls and the change in gravitational potential energy goes entirely into work to compress the thighbone, what is the maximum height that the man's centre of mass can fall under gravity without breaking his thighbone?