Acable consists of a steel wire 2.5mm in diameter, surrounded by six bronze wires of the same size. if the allowable stress in the bronze is 60mpa, find the safe load for the cable and the extension under this load on the length of 30m (est= 200gpa and ebr = 80gpa).

Different types of steels contain different elements that alter the characteristics of the steel. for each of the following elements, explain what the element does when alloyed with steel.

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 the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct.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

Air is flows through an adiabatic nozzle with an inlet pressure of 400 psia at a temperature of 300°f and a velocity of 20 ft/s. the outlet pressure is 40 psia and the velocity is 800 ftl/s. determine the outlet temperature of the air using: a) property tables b) specific heat (using the specific heat value for air at 300°f)