Question

1. A polyethylene rod exactly 10 inches long with a cross-sectional area of 0.04 in² is used to suspend a weight of 514 lbs-f (pounds-force). Given the tensile modulus for this polymer is  25,000 psi and the viscosity is 3 × 10⁹ psi-sec, calculate the length of the rod, in inches, 1 hour(s) after loading.

Answer Format: X.XX

Unit: inches

2. A polymeric cylinder initially exerts a stress with a magnitude (absolute value) of 1.437 MPa when compressed. If the tensile modulus and viscosity of this polymer are 16.5 MPa and 2 ×1012 Pa-s, respectively, what will be the approximate magnitude of the stress, in MPa, exerted by the spring after 1.8 day(s)?

Answer Format: X.X

Unit: MPa

Answer 1