The solid shaft shown in the figure below is fixed at one end and has a lever at the

other. The shaft is supported by two bearings. A force $F$ of $1,650N$ is applied at the

end of the lever, a distance of $b$ from the centre line of the shaft. A shear stress of

$970\frac{N}{m}{m}^2$ is induced at point A $,$ on the outer surface of the shaft, a distance a of

$\{$a$\}$ mm along the shaft from the lever. The shaft has a diameter of $10$ mm $.$ Find the

value of $b.$ Give your answer in mm to $3$ significant figures.