A 91 kg man's thighbone has a relaxed length of 0.50m, a cross-sectional area of $7.0 \times 10^{-4} \mathrm{~m}^{2}$ and a young's modulus of $1.1 \times 10^{11} \mathrm{~N} / \mathrm{m}^{2}$ . By how much does the thighbone compress when the man is standing on both feet?