3. an 8-inch diameter steel shaft is force fit into a cast iron disk with a 20-inch outside diameter. the maximum tangential stress in the disk is 5000 psi. if esteel = 30x106 psi and ecast iron = 15x106 psi, with poisson’s ratio  for both materials equals to 0.3, (a) determine the contact pressure required between the shaft and the disk (a: p  3621 psi ). (b) determine the decrease in the radius of the shaft (a: ds = 0.00034 inch). (c) determine the required diametral interference (a: 2 = 004 in. (hint: a change in the shaft radius or diameter can be obtained through the displacement in the shaft)

Determine the time of the day and month of the year at which the peak sensible cooling load occurs for a top floor, north-eastern corner room of an office building in durban for the following conditions: floor area: 8 x 8 x 3 m east and north walls: 115 mm face brick (outside), 20 mm air space, 115 mm ordinary brick (inside) with 15 mm plaster roof construction: suspended plasterboard ceiling, 450 mm air space, 150 mm concrete, 75mm screed, waterproofing no heat transfer across other surfaces window area 3x 1,5 m high in north wall only. ordinary glass with venetian blinds. lights and occupants : from 07: 00 to 18: 00 average light density: 25 w/m2 number of occupants : 5 seated, light office work room temperature 24°c