Maths questions full workings out please and engineering question explain in detail please

Question 1: A tensile load F is to be applied to a tie bar shown in figure. The tie bar is 50 mm diameter. The surface of the bar has defects resulting from the manufacturing process, these have a maximum depth of 1.5 mm and have a shape factor of 1.4.

If the fracture toughness of the material used is 120 MPa m^-0.5, determine the maximum load which can be applied if brittle fracture is not to occur. Use a factor of safety of 3.

Question 2: Consider that we need to predict the fatigue life of the bracket shown in figure. If we are given that the following relationship applies for the bracket:

Da/dV = 4 x 10^-12 (ΔK)³   where Δk is in MPa m^1/2

and  that the stress varies cyclically between 30 and 150 MPa, determine the number of cycles for a defect to grow from 1.5mm to 4 mm.