Asquare thread power screw is designed to provide 150n of lifting force at a rate of 15mm/s. the power screw is driven directly by a motor. the screw has a nominal diameter of 12mm and a pitch of 3mm. the screw-nut combination has a coefficient of friction of 0.06 and there is a 30mm diameter collar with a coefficient of friction of 0.08. a. determine the total torque required to lift the load as described b. determine the required power of the motor c. determine the factor of safety for torsion failure at the root diameter

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?