(a) Distinguish between stress and strain as used in elasticity.
(b) When a force of 40 N is applied to the free end of an elastic cord, an extension of 5cm is produced in the cord. Calculate the work done on the cord.
Verified Correct Answer: .
Physical Principles & Numerical Solution
(a)(i) Stress is force per unit cross sectional area, while strain is extension over original length
(ii) Stress has unit of Nm\(^{-2}\) while strain has no unit.
(b) Work done on the cord = \(\frac{1}{2}\) Fe
= \(\frac{1}{2}\) x 40 x 0.05 = 1.0J
Source: Myschool Past Questions Archive (Record #54123)