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 = \(\frac{\text{weight in air}}{\text{upthrust}} = \frac{10}{10.5 - 6.8} = \frac{10.5}{3.7} = 2.84\)


