The one end of a hollow square bar whose side is (10+N/100) in with (1+N/100) in thickness is under a tensile stress 102,500 psi and the other end is connected with a U bracket using a double-pin system. Find the minimum diameter of pin is used according to shear strength. Take the factor of safety as 1.5 and σ_all=243 ksi for pin material. n=1

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

Aquick transition of the operating speed of a shaft from its critical speed will whirl amplitude. (a) increase (b) limit (c) not affect (d) zero

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 the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct.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.