The a-36 steel axle is made from tubes ab and cd and a solid section bc. it is supported on smooth bearings that allow it to rotate freely. the tubes have an outer diameter of 30 mm and an inner diameter of 20 mm. the solid section has a diameter of 40 mm.

if the gears, fixed to its ends, are subjected to 85? n? m torques, determine the angle of twist of gear a relative to gear d.

Apreheater involves the use of condensing steam at 100°c on the inside of a bank of tubes to heat air that enters at 1 atm and 25°c. the air moves at 5 m/s in cross flow over the tubes. each tube is 1 m long and has an outside diameter of 10 mm. what is the minimum value of nl needed to achieve an outlet temperature of t 75 c? what is the corresponding pressure drop across the tube bank?