Consider a viscoelastic polymer rod that is stretched from 100 mm to 165 mm by a stress of 3.35 MPa. While being held at the same strain, the stress drops to 2.04 MPa after 60 seconds due to stress relaxation.
(a) How long does it take for the stress to drop to 1/2 of its initial magnitude?
(b) What is the modulus of elasticity (relaxation modulus) when the stress is reduced by 1/2?