A hollow stainless steel shaft with an outside diameter of 42 mm and a wall thickness of 4 mm has an allowable shear stress of 100 MPa. Determine the maximum torque T that may be applied to the shaft.

Estimate the change in specific internal energy au and specific enthalpy h from inlet to outlet for ethylene glycol (a liquid) flowing through each of the following devices: (a) a heat exchanger where the glycol temperature increases from 20 °c to 80 °c; (b) a pump operating at about 25 °c and increasing the glycol pressure from 100 kpa to 8 mpa.