3. The load-elongation curve represents results of a tensile test of a cylindrical specimen (initial diameter is 4 mm, gauge length is 25 mm). Estimate the Young's modulus. (3 points) Load (kN) 2.5 1.5 1 2 3 0.5 0 0 0.025 0.05 0.075 0.1 0.125 0.15 0.175 0.2 Elongation (mm) 4. Elastic modulus of a steel changes significantly (10% or more) as a function of the carbon content. (1 point) (a) True (b) False 7. An external force of F is applied to a cube as shown on the figure. Material is isotropic. Determine strain and stress tensor (matrix form, = [01,02, ..., 06]) qualitatively (+, -, 0). (Mind the constrains.) (2 points) 2 1 F - Constrained from expansion or contraction along axis 1 F Free to expand or contract along axes 2 and 3