An internal gear is set up with a 5-in diameter pinion and center distance of 18 inches. Find the diameter of the internal gear.

Determine the average shear stress in the 20-mm-diameter pin at A and the 30-mm-diameter pin at B that support the beam shown below. 

The boom AC is a 4-in. square steel tube with a wall thickness of 0.25 in. The boom is supported by the 0.-in, diameter pin at A, and the 0.375-in diameter cable BC. The working stresses are 25 ksi for the cable. 18ksi for the boom, and 13.6 ksi for shear in the pin. Neglecting the weight of the boom, determine the largest safe load P that can be applied as shown. 

Compute the diameter of a mild steel rod which have been cold 
worked to 27.59% having original diameter of 23.15mm?

plz answer its question.