A 300-mm-long, solid, straight shaft is supported in self-aligning bearings at each end. A gear is attached at the middle of the shaft with a 10-mm square steel key in a slot. The geometric stress-concentration factor in the keyslot is 2.5 and its corner radius is 0.5 mm. The gear drives a fluctuating load which creates a bending moment that varies from +10N-m to +100 N-m and a torque that varies from –35 N-m to +170 N-m each cycle. The material chosen is cold-drawn 4140 steel, hardened and tempered to Rockwell C45 (Sut = 1250 MPa). Design the shaft for infinite life and determine diameter needed for safety factor of 1.5.

The temperature of air decreases as it is compressed by an adiabatic compressor. a)- true b)- false

Water at 70°f and streams enter the mixing chamber at the same mass flow rate, determine the temperature and the quality of the exiting stream. 0 psia is heated in a chamber by mixing it with saturated water vapor at 20 psia. if both streams enters the mixing chamber at the same mass flow rate, determine the temperature and the quality of the existing system.

A3-mm-thick panel of aluminum alloy (k 177 w/m-k, c 875 j/kg-k and ? = 2770 kg/m) is finished on both sides with an epoxy coating that must be cured at or above t,-150°c for at least 5 min. the production line for the curing operation involves two steps: (1) heating in a large oven with air at ts,0-175°c and a convection coefficient of h, 40 w/m2. k, and (2) cooling in a large chamber with air at 25°c and a con- vection coefficient of he 10 w/m2.k. the heating portion of the process is conducted over a time interval te which exceeds the ime required to reach 150°c by 5 min (h = r + 300 s). the coating has an emissivity of ? = 0.8, and the temperatures of the oven and chamber walls are 175 and 25°c, respectively. if the panel is placed in the oven at an initial temperature of 25°c and removed from the chamber at a safe-to-touch tempera ture of 37°c, what is the total elapsed time for the two-step curing operation?