For a bolted assembly with six bolts, the stiffness of each bolt is kb 5 3 mlbf/in and the stiffnessof the members is km 5 12 mlbf/in per bolt. an external load of 80 kips is applied to theentire joint. assume the load is equally distributed to all the bolts. it has been determined touse 12 in-13 unc grade 8 bolts with rolled threads. assume the bolts are preloaded to 75 percentof the proof load.(a) determine the yielding factor of safety.(b) determine the overload factor of safety.(c) determine the factor of safety based on joint separation

To save energy, the air supply to a 2000 ft office has been shut off overnight and the room temperature has dropped to 40°f. in the morning, the thermostat is reset to 70°f and warm air at 120 f begins to flov in at 200ft'/min. the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct. the air pressure is nearly 1 atm everywhere. ignoring heat transfer with the surroundings and kinetic and potential energy effects, estimate how long it takes for the room temperature to reach 70°f. plot the room temperature as a function of time.