Find the minimum diameter of a solid circular shaft if it has a maximum shear stress of 53 mpa and it is to transmit 28 kw of power at a rotational speed of 2,516 rpm. enter your numerical value below for minimum diameter, d, in units of millimeters. enter your answer to one decimal place and the result must be within +/- 1% of the correct value to be counted as correct.

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.