(a) State Hooke’s law of elasticity
(b) A spiral spring, loaded with a piece of metal, extends by 10.5cm hair. When the metal is fully submerged in water, the spring extends by 6.8cm. Calculate the relative density of the metal. (Assume Hooke’s law is obeyed).
Explanation
(a) Hooke's law states that the force applied on an elastic materal is proportional to its extension, provided the elastic limit is not exceeded
(b) R.D = \(\frac{\text{weight in air}}{\text{upthrust}} = \frac{10}{10.5 - 6.8} = \frac{10.5}{3.7} = 2.84\)