State Hooke’s law in its shear stress-strain form and define each quantity in the equation

a) State Hooke’s law in its shear stress-strain form and define each quantity
in the equation.
[4 marks]

b) What is meaning of the phrase ‘coplanar and concurrent’ when describing
a force system?
[2 marks]

c) Write down the (independent) equations of static equilibrium for such a
force system described in part b).
[1 mark]

d) A tensile force of 5 KN is applied axially to 250 cm-long rod with a
diameter of 3 cm, a Young’s modulus of 70 GPa, and a Poisson’s ratio of
0.3.

(i) What is the elongation of the rod?

[4 marks]

(ii) What is the change in the diameter of the rod?

[4 marks]