Question

1. A mad scientist decides to perform an experiment on the tensile strength of living bone. With each change in stress (measured in MPa), he records the strain on the bone and obtains the following data. At 91 MPa the bone fractures and breaks.

Stress	Strain
0	0
5	0.01
10	0.02
20	0.03
30	0.04
40	0.05
50	0.06
60	0.07
70	0.08
80	0.09
81	0.11
85	0.14
90	0.17

1A) Plot the data; identify the elastic region, the plastic region, the yield point, and the ultimate strength.

1B) Calculate Young’s Modulus (modulus of elasticity) for the data.

1C) If the bone was 27 cm long just before it fractured, estimate its initial length.

1D) How might you explain the observation that bone lengthens more rapidly at low stress (say ~0.1 MPa) than at higher stress (~0.6 MPa), and how might this be used advantageously by an organism during locomotion?

Answer 1